Update README.md

Header 2 for docs header

Author: D1M1TR10S

README.md

@@ -28,7 +28,7 @@ or in watch mode:
 npm run dev
 ```
 
-**Documentation:**
+## Documentation
 - [Using Copilot Extensions](https://docs.github.com/en/copilot/using-github-copilot/using-extensions-to-integrate-external-tools-with-copilot-chat)
 - [About building Copilot Extensions](https://docs.github.com/en/copilot/building-copilot-extensions/about-building-copilot-extensions)
 - [Set up process](https://docs.github.com/en/copilot/building-copilot-extensions/setting-up-copilot-extensions)