Link in notification for new Peertube version should point to release notes

[JohnXLivingston]

Describe the problem to be solved

When a new Peertube version is available, we receive a notification:

Currently, the link in this notification points to https://joinpeertube.org/news

This page contains news only for major releases (and the news can be published several days after the notification).
It does not say anything for minor releases (as for the v5.0.1 that was published today).

Moreover, we often see on the Peertube forum administrators that did not read the importants changelog's notes, and forgot to change configuration or apply manual migration scripts.

Describe the solution you would like

I think the link should point to something containing the changelog (and migration notes):

• https://github.com/Chocobozzz/PeerTube/releases
• or https://github.com/Chocobozzz/PeerTube/blob/master/CHANGELOG.md