v1.4.0: docs: add "Why RTR" comparison table to README
- Add comparison table highlighting RTR's advantages over httprouter, chi, and gorilla - Rename "Features" section to "Key Features" - Streamline README by moving detailed docs to separate files
- Add comparison table highlighting RTR's advantages over httprouter, chi, and gorilla - Rename "Features" section to "Key Features" - Streamline README by moving detailed docs to separate files