Add license and Google attribution

[komodo170845]

What changed

• licenses the Markdown documentation under CC BY 4.0
• licenses the validator, tests, and workflow under MIT
• credits the Google developer documentation style guide and identifies the modified material
• updates the README to explain commercial use and point to the licensed v1.0.1 package

Why

The project adapts Google guidance that permits commercial reuse under CC BY 4.0. The repository needed an explicit attribution notice and a clear boundary between documentation and software licensing.

Checks

• skill validation passed
• Markdown validation passed for 8 files
• 4 unit tests passed
• git diff --check passed