Repository archive date now shown in UI

In a small but frequently requested improvement, GitHub now shows the date that an archived repository was put into read-only mode to indicate it is no longer actively maintained.

Previously, you could see that a repo was in the 'archived' state and probably infer from the commit log when it last saw activity, but the actual date the archiving happened was not surfaced anywhere. Now there's a date included in the "this repo is read-only" banner at the top of the repository view.

Repositories archived prior to November 9th, 2022, will display a more generic message.