Show documentation on plugins site

[MarkEWaite]

Show documentation on plugins.jenkins.io

Current plugin page does not show documentation

Testing done

Checked that the URL from the previous release resolved to the repository. Did not understand why plugins.jenkins.io generator could not find the asciidoc files that documents the plugin.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue