Add health check for .well-known issues

[obenland]

What

Beyond the check whether .well-known works and is available, it could include troubleshooting tips and a link to predefined templates to contact hosts to enable it.

Why

We get a considerable support volume with .well-known issues, hopefully this would help.

How

No response

[github-actions]

This issue could use some more labels, to help prioritize and categorize our work. Could you please add at least a [Type], a [Feature], and a [Pri] label?