📝 Update User Guide with Latest Features

[mlamina]

This PR updates the user guide and documentation to reflect the latest features and improvements in PR Pilot.

Summary of changes:

Documentation Updates

• Remove outdated roadmap from README.md and docs/source/roadmap.md
• Update docs/source/index.rst to link to the new integrations page and demo repository
• Add new integrations page in docs/source/integrations.md
• Update docs/source/support.md to include discussions and feature requests
• Update docs/source/team.md with latest team information
• Enhance docs/source/user_guide.md with detailed instructions and examples
• Remove roadmap link from docs/source/vision.md

Code Changes

• Update end-to-end test in e2e_test.py to reflect new Linear task
• Revise login page template in templates/socialaccount/login.html to improve user onboarding experience