add more info to changelogs

[eristhea]

• check maven metadata to determine:
  • whether a version is released
  • if so, the release date
• link original changelog file
• link project and relevant pages

[eristhea]

another cool feature for the changelog page would be making the main content on https://quiltmc.org/en/changelog/ a truncated stream of the latest updates instead of a flat list of pages, since that's already on the sidebar