Move ENVIRONMENT.md and SECURITY.md to docs/ with lowercase naming (#17)

* Initial plan

* Initial plan for moving and renaming documentation files

Co-authored-by: Mossaka <5447827+Mossaka@users.noreply.github.com>

* Move ENVIRONMENT.md and SECURITY.md to docs/ and rename to lowercase

Co-authored-by: Mossaka <5447827+Mossaka@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Mossaka <5447827+Mossaka@users.noreply.github.com>

Author: Copilot

CLAUDE.md

@@ -9,7 +9,7 @@ This is a firewall for GitHub Copilot CLI (package name: `@github/awf`) that pro
 ### Documentation Files
 
 - **[README.md](README.md)** - Main project documentation and usage guide
-- **[ENVIRONMENT.md](ENVIRONMENT.md)** - Environment variable configuration and security best practices
+- **[docs/environment.md](docs/environment.md)** - Environment variable configuration and security best practices
 - **[LOGGING.md](LOGGING.md)** - Comprehensive logging documentation
 - **[docs/logging_quickref.md](docs/logging_quickref.md)** - Quick reference for log queries and monitoring