Add development documentation section to the README

README.md

@@ -10,3 +10,26 @@ Install the extension from the Marketplace, execute the command `Preferences:
 Product Icon Theme` and select the entry `EOS Icons` in the presented drop down:
 
 ![select_product_theme.png](select_product_theme.png)
+
+
+## Development
+
+To build the extension yourself, you will need the following packages installed:
+
+- nodejs
+- yarn
+- python
+
+and execute the following commands to setup your development environment:
+```ShellSession
+$ yarn install
+$ yarn run prepare
+```
+
+To build the extension itself, execute `yarn run package`.
+
+To try the extension out in VSCode, open this folder in VSCode and press `<f5>`
+to launch a debugging session. This will create a fresh VSCode instance with the
+extension pre-installed and loaded. Note that sometimes the icon theme is not
+properly loaded on launch, in that case switch the Product Icon Theme to the
+default and back to EOS Icons.