fix: correct GitHub URL in contributing page (nTEG-dev -> gitmem-dev)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: 2 people

apps/docs/content/docs/contributing/index.mdx

@@ -10,7 +10,7 @@ GitMem is open source. Contributions are welcome.
 ## Development Setup
 
 ```bash
-git clone https://github.com/nTEG-dev/gitmem
+git clone https://github.com/gitmem-dev/gitmem
 cd gitmem
 npm install
 npm run build