* leverage yamllint in GitHub actions * add pre-commits * validation updates * Update README.md * Update CONTRIBUTING.md
* Create OS6450-24.yaml * Create OS6450-48.yaml * Create OS6450-P24.yaml * Create OS6450-P48.yaml * Create OS6860-48.yaml * Create OS6860E-24.yaml * Create OS6860E-48.yaml * Create OS6860E-U28.yaml * Create OS6900-X20.yaml * Create OS6900-X40.yaml