style(action.yml): reformat branding section to be more readable and consistent with the rest of the file

feat(action.yml): add keywords to improve discoverability of the action

Author: di-sukharev

action.yml

@@ -2,8 +2,9 @@ name: 'OpenCommit — improve commits with AI 🤯🔫'
 description: 'Replaces lame commit messages with meaningful AI-generated messages when you push to remote'
 author: 'https://github.com/di-sukharev'
 repo: 'https://github.com/di-sukharev/opencommit/tree/github-action'
-icon: 'git-commit'
-color: 'green'
+branding:
+  icon: 'git-commit'
+  color: 'green'
 keywords:
   [
     'git',