Readme fixes (rerun-io#6308)

### What

* Fix accidental h1 heading on CONTRIBUTING.md
* Various small updates to README.md

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6308?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6308?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/6308)
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

To run all checks from `main`, comment on the PR with `@rerun-bot
full-check`.

ARCHITECTURE.md

@@ -18,14 +18,14 @@ The logging SDK:s encodes the data using Apache Arrow (see more below).
 
 The logging data can be written to disk as `.rrd` files, or transmitted over TCP to either a Rerun Viewer or a Rerun Server.
 
-### Rerun viewer
+### Rerun Viewer
 The Rerun Viewer is where log data is visualized. It is usually run as a native app, but can also be compiled to WebAssembly (Wasm) and run in a browser.
 
-#### Native viewer
-The easiest way to launch the viewer is directly from the logging API with `rr.init("rerun_example_app", spawn=True)`. However, the standalone viewer can also be run from the command line, for example to view an `.rrd` file: `rerun mydata.rrd`.
+#### Native Viewer
+The easiest way to launch the Viewer is directly from the logging API with `rr.init("rerun_example_app", spawn=True)`. However, the standalone Viewer can also be run from the command line, for example to view an `.rrd` file: `rerun mydata.rrd`.
 
 #### Web viewer
-You can try running the viewer in a browser using `rr.serve()` in python, or using `rerun --web-viewer mydata.rrd`.
+You can try running the Viewer in a browser using `rr.serve()` in python, or using `rerun --web-viewer mydata.rrd`.
 
 The web viewer consists of just a few small files - a thin `.html`, a `.wasm` blob, and an auto-generated `.js` bridge for the wasm. These files are served using the [`re_web_viewer_server`](https://github.com/rerun-io/rerun/tree/latest/crates/re_web_viewer_server) crate.
 
@@ -113,7 +113,7 @@ Update instructions:
 | Crate     | Description                          |
 |-----------|--------------------------------------|
 | rerun-cli | Rerun native CLI binary crate        |
-| rerun     | Rerun Rust SDK and viewer shim crate |
+| Rerun     | Rerun Rust SDK and Viewer shim crate |
 | rerun_c   | Rerun C SDK                          |
 | rerun_py  | Rerun Python SDK                     |
 | re_sdk    | Rerun logging SDK                    |
@@ -126,11 +126,11 @@ Update instructions:
 
 | Crate                       | Description                                                                            |
 |-----------------------------|----------------------------------------------------------------------------------------|
-| re_viewer                   | The Rerun viewer                                                                       |
+| re_viewer                   | The Rerun Viewer                                                                       |
 | re_viewport                 | The central viewport panel of the Rerun viewer.                                        |
 | re_time_panel               | The time panel of the Rerun Viewer, allowing to control the displayed timeline & time. |
 | re_data_ui                  | Provides ui elements for Rerun component data for the Rerun Viewer.                    |
-| re_viewer_context           | Rerun viewer state that is shared with the viewer's code components.                   |
+| re_viewer_context           | Rerun Viewer state that is shared with the viewer's code components.                   |
 | re_ui                       | Rerun GUI theme and helpers, built around egui                                         |
 | re_renderer                 | A wgpu-based renderer for all your visualization needs.                                |
 | re_space_view               | Types & utilities for defining Space View classes and communicating with the Viewport. |
@@ -170,7 +170,7 @@ Update instructions:
 |----------------------|--------------------------------------------------------------------------------------------------------|
 | re_sdk_comms         | TCP communication between Rerun SDK and Rerun Server                                                   |
 | re_web_viewer_server | Serves the Rerun web viewer (Wasm and HTML) over HTTP                                                  |
-| re_ws_comms          | WebSocket communication library (encoding, decoding, client, server) between a Rerun server and viewer |
+| re_ws_comms          | WebSocket communication library (encoding, decoding, client, server) between a Rerun server and Viewer |
 | re_data_loader       | Handles loading of Rerun data from file using data loader plugins                                      |
 | re_data_source       | Handles loading of Rerun data from different sources                                                   |
 

BUILD.md

@@ -31,7 +31,7 @@ If you are using an Apple-silicon Mac (M1, M2), make sure `rustc -vV` outputs `h
 rustup set default-host aarch64-apple-darwin && rustup install 1.76.0
 ```
 
-## Building and running the viewer
+## Building and running the Viewer
 
 Use this command for building and running the viewer:
 
@@ -57,12 +57,12 @@ Rerun is available as a package on PyPi and can be installed with `pip install r
 
 Additionally, nightly dev wheels from head of `main` are available at <https://github.com/rerun-io/rerun/releases/tag/prerelease>.
 
-If you want to build from source, you can do so easily in the pixi environment:
-* Run `pixi run py-build --release` to build SDK & viewer for python (or `pixi run py-build` for a debug build)
-* Then you can run examples from the repository, either by making the pixi shell active with  `pixi shell` and then running python or by using `pixi run`, e.g. `pixi run python examples/python/minimal/minimal.py`
+If you want to build from source, you can do so easily in the Pixi environment:
+* Run `pixi run py-build --release` to build SDK & Viewer for Python (or `pixi run py-build` for a debug build)
+* Then you can run examples from the repository, either by making the Pixi shell active with  `pixi shell` and then running Python or by using `pixi run`, e.g. `pixi run Python examples/python/minimal/minimal.py`
 
 
-### Tests & Tooling
+### Tests & tooling
 
 ```sh
 # Run the unit tests
@@ -75,12 +75,12 @@ pixi run py-lint
 pixi run py-fmt
 ```
 
-### Building an installable Python Wheel
+### Building an installable Python wheel
 The `py-wheel` command builds a whl file:
 ```sh
 pixi run py-wheel --release
 ```
-Which you can then install in your own python environment:
+Which you can then install in your own Python environment:
 ```sh
 pip install ./target/wheels/*.whl
 ```
@@ -100,16 +100,16 @@ pixi run cpp-build-all
 
 ## Building the docs
 
-High-level documentation for rerun can be found at [http://rerun.io/docs](http://rerun.io/docs). It is built from the separate repository [rerun-docs](https://github.com/rerun-io/rerun-docs).
+High-level documentation for Rerun can be found at [http://rerun.io/docs](http://rerun.io/docs). It is built from the separate repository [rerun-docs](https://github.com/rerun-io/rerun-docs).
 
 - 🌊 [C++ API docs](https://ref.rerun.io/docs/cpp) are built with `doxygen` and hosted on GitHub. Use `pixi run cpp-docs` to build them locally. For details on the C++ doc-system, see [Writing Docs](rerun_cpp/docs/writing_docs.md).
-- 🐍 [Python API docs](https://ref.rerun.io/docs/python) are built via `mkdocs` and hosted on GitHub. For details on the python doc-system, see [Writing Docs](rerun_py/docs/writing_docs.md).
+- 🐍 [Python API docs](https://ref.rerun.io/docs/python) are built via `mkdocs` and hosted on GitHub. For details on the Python doc-system, see [Writing Docs](rerun_py/docs/writing_docs.md).
 - 🦀 [Rust API docs](https://docs.rs/rerun/) are hosted on  <https://docs.rs/rerun/>. You can build them locally with: `cargo doc --all-features --no-deps --open`.
 
 ## Building for the web
 
-If you want to build a standalone rerun executable that contains the web-viewer and a websocket server,
-you need to install the `wasm32-unknown-unknown` rust target and ensure the `web_viewer` feature flag is set when building rerun.
+If you want to build a standalone Rerun executable that contains the web-viewer and a websocket server,
+you need to install the `wasm32-unknown-unknown` Rust target and ensure the `web_viewer` feature flag is set when building rerun.
 This is automatically done by this shortcut which builds & runs the web viewer:
 ```
 pixi run rerun-web