add some development notes to readme

README.md

@@ -5,3 +5,13 @@
 Tako is an inline, expandable file tree with file preview for github. [Get it on the Chrome Webstore!](https://chrome.google.com/webstore/detail/tako-%E2%80%94-github-file-tree/fdmdpnmffpjdkjaapcbdnkhnidhgoabe)
 
 ![](media/screenshot.png)
+
+## Development
+
+- `git clone`
+- `cd tako`
+- `yarn install`
+- `yarn start`
+- [Turn on dev mode for chrome extensions](https://developer.chrome.com/extensions/faq#faq-dev-01)
+- Click "Load unpacked" and select `tako/unpacked-extension`
+- Navigate to any github repository and open dev tools