Add documentation for GitHub Action issue-comment.yml

[bhouston]

Add documentation for GitHub Action issue-comment.yml

We need to create a new page in the Usage documentation section that explains how to use the GitHub Action issue-comment.yml from the mycoder project. This action allows users to trigger mycoder to run via comments on issues or PRs.

Documentation should cover:

• How the GitHub Action works
• Benefits of using mycoder via issue/PR comments
• Best practices for setup:
  • Using a Personal Access Token instead of the built-in GitHub Token
  • Running with userPrompt = false
  • Git configuration for commits
  • Security considerations for restricting execution to trusted individuals
• Example usage and configuration

Location

The new documentation should be added to the /docs/usage/ directory as a new markdown file.