Some plugins specify a GitHub repository as its documentation URL as provided via https://updates.jenkins-ci.org/current/plugin-documentation-urls.json, e.g. https://plugins.jenkins.io/codescene

Right now, it's relatively few plugins. Ideally this feature enables moving plugin documentation out of the wiki.

The feature

Similar to how the wiki works, add support for inlining GitHub repository README files.

The API is: https://developer.github.com/v3/repos/contents/#get-the-readme

It can return the rendered HTML.

This must be limited to plugins with GitHub repositories in the jenkinsci organization.

I.e. codescene (above) gets inline doc, https://plugins.jenkins.io/chef does not (documentation URL doesn't point to jenkinsci organization).

Out of scope: Support for arbitrary files, different branches, etc.

Configuration and errors

It needs support for specifying a GH access token for the plugin site. Must be an environment option like other Jenkins infra credentials.

Local copy of the content should be cached, like wiki pages.

If the rate limit is reached, or the API returns another error (no README, repo doesn't exist, etc.) should fall back to showing a link, similar to wiki pages that cannot be retrieved.