Update index.md (MystenLabs#992)

Add File issues section pointing to our new template
Move docs feedback section from Lean index

doc/src/contribute/index.md

@@ -26,6 +26,20 @@ To submit your pull request:
 6. Complete the Contributor License Agreement (CLA), if you haven't already done so.
 7. Submit your pull request.
 
+## File issues
+
+Report bugs and make feature requests in the [Sui GitHub](https://github.com/MystenLabs/sui/issues) repository
+using the [Template for Reporting Issues](https://github.com/MystenLabs/sui/blob/main/ISSUES.md).
+
+## Provide docs feedback
+
+Send us documentation fixes or requests for improvement at:
+[email protected]
+
+You may also suggest changes to the docs directly in GitHub right here using the **Source Code** link below.
+
+Simply edit the file in question and generate a pull request. We will get back to you shortly.
+
 ## Further reading
 
 * Learn [about Mysten Labs](https://mystenlabs.com/) the company on our public site.