docs: clarify documentation commit format with file extension example

- Add .md file extension guidance for documentation changes in commit message examples
- Improve clarity for contributors on proper docs commit formatting

This follows the existing pattern and provides helpful guidance for contributors about the expected format when making documentation changes.

Author: JohannLai

src/claude_commit/main.py

@@ -117,7 +117,7 @@
 - If no clear pattern exists in history, use conventional commits format:
   * feat: for new features
   * fix: for bug fixes
-  * docs: for documentation changes
+  * docs: for documentation changes, add .md to the end of the file name
   * refactor: for code refactoring
   * test: for test changes
   * chore: for chore changes