docs: Fix README - remove duplicates and clean up setup section

- Remove duplicate repository links
- Fix duplicate/conflicting installation steps
- Complete Quick Setup Overview with proper steps 7-9
- Replace old numbered sections with streamlined overview
- Add links to detailed guides

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: shubham5080

README.md

@@ -87,8 +87,6 @@ Gitcord is a local, offline‑first automation engine that reads GitHub activity
 1. [Main Repository](https://github.com/AOSSIE-Org/Gitcord-GithubDiscordBot)
 2. [Installation Guide](INSTALLATION.md) - Complete setup instructions
 3. [Technical Documentation](TECHNICAL_DOCUMENTATION.md) - Architecture and design
-2. [Installation Guide](INSTALLATION.md) - Complete setup instructions
-3. [Technical Documentation](TECHNICAL_DOCUMENTATION.md) - Architecture and design
 
 ---