Revert filename changes - keep original names

Reverted Step 2 filename changes:
- how-it-works.md → how-react-on-rails-works.md
- overview.md → react-on-rails-overview.md
- server-rendering.md → react-server-rendering.md
- auto-bundling.md → auto-bundling-file-system-based-automated-bundle-generation.md

Rationale:
- Filenames are content, not structure
- Current phase is reorganization (moving files), not content changes
- Renaming should be discussed separately as content improvement
- Consistent with Decision 2: keep descriptive names

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ihabadham