Provide context to dispatched PRs

[ChristophWurst]

When something like nextcloud-libraries/nextcloud-sharing#2 pops up in my notifications it always takes me a few moments to figure out what a change does, why we need it and what I have to test or pay attention to.

I think we can do better than this. Maybe draw some inspiration from Dependabot.

Would the automation be able to derive that from the information in git?

[skjnldsv]

That would be awesome!
No idea if we can do that, let me check what inputs can be provided on a manual workflow run

[szaimen]

Alternative: #244