[JENKINS-64666] document urls

[tszmytka]

See JENKINS-64666.
Document modules with project urls. This will allow /about page to build correct links.

Proposed changelog entries

Provide working "Help About" links for Jenkins CLI, Jenkins core, and Jenkins war

Proposed upgrade guidelines

N/A

Submitter checklist

• (If applicable) Jira issue is well described
• Changelog entries and upgrade guidelines are appropriate for the audience affected by the change (users or developer, depending on the change). Examples
  • Fill-in the Proposed changelog entries section only if there are breaking changes or other changes which may require extra steps from users during the upgrade
• Appropriate autotests or explanation to why this change has no tests
• For dependency updates: links to external changelogs and, if possible, full diffs

Maintainer checklist

Before the changes are marked as ready-for-merge:

• There are at least 2 approvals for the pull request and no outstanding requests for change
• Conversations in the pull request are over OR it is explicit that a reviewer does not block the change
• Changelog entries in the PR title and/or Proposed changelog entries are correct
• Proper changelog labels are set so that the changelog can be generated automatically
• If the change needs additional upgrade steps from users, upgrade-guide-needed label is set and there is a Proposed upgrade guidelines section in the PR title. (example)
• If it would make sense to backport the change to LTS, a Jira issue must exist, be a Bug or Improvement, and be labeled as lts-candidate to be considered (see query).

[MarkEWaite]

I confirmed that the links are broken in Jenkins 2.289.2 and work in Jenkins 2.305-SNAPSHOT as built from this pull request. Fixed links include:

• Jenkins CLI
• Jenkins core
• Jenkins war

[MarkEWaite]

This PR is now ready for merge. We will merge it after approximately 24 hours if there is no negative feedback.

[oleg-nenashev]

Fine with me, thanks!

We may merge it in 24 hours if there is no negative feedback. Please see the merge process documentation for more information about the merge process