The releases-documentation is misleading/incorrect/lacking

The documentation on releases that you find via a google-search or just manually navigating to docs.buildbot.net dont mention anything about a move to github for 'further' releases/release-notes.

It turns out there are two new releases after 3.6.0 I had no inkling of, no mention was made of them on the website.

I would suggest at least adding a reference somewhere that certain parts (releasenotes, versions, ....others?) have moved to Github.

I've had a babylonian misunderstanding with a colleague due to him landing on Github for his info, and me searching the official website docs for info.

Start with the releases documentation reachable from docs.buildbot.net and compare it with the release notes and version information on GitHub, especially after 3.6.0. Update the relevant documentation to clearly direct readers to GitHub for material that moved there, and verify that the website no longer presents incomplete release information.

Written by the indexing model from the issue text.