chore: add local testing guide to CONTRIBUTING#210

ibrahimcesar merged 1 commit intomainibrahimcesar/react-lite-youtube-embed:mainfrom

claude/document-local-script-testing-01Kz1cHfW1cFFfixvPWUD1vGibrahimcesar/react-lite-youtube-embed:claude/document-local-script-testing-01Kz1cHfW1cFFfixvPWUD1vGCopy head branch name to clipboard