cleanup: update PDF README

scripts/pdf/README.md

@@ -11,19 +11,25 @@ This directory contains the script and related resources to generate a PDF docum
 
 The PDF is generated by first converting the Markdown files to HTML, and then rendering those HTML files as a PDF. It depends on the `markdown` and `weasyprint` libraries. To install the dependencies, run:
 
-    python3 -m pip install -r requirements.txt
+```sh
+python3 -m pip install -r requirements.txt
+```
 
-Make sure OS specific dependencies for WeasyPrint are installed by following the instructions [here](http://weasyprint.readthedocs.io/en/latest/install.html).
+Make sure OS-specific dependencies for WeasyPrint are installed by following the instructions [here](https://doc.courtbouillon.org/weasyprint/stable/first_steps.html#installation).
 
 ## Usage
 
 Generating the PDF is as simple as running:
 
-    python3 render.py <path-to-pages-directory> [--color <color-scheme>] [--output <filename>] [--platform <platform-name>]
+```sh
+python3 render.py <path-to-pages-directory> [--color <color-scheme>] [--output <filename>] [--platform <platform-name>]
+```
 
 Complete information about the arguments can be viewed by running:
 
-    python3 render.py --help
+```sh
+python3 render.py --help
+```
 
 Available color schemes: