mod_rest/apidemo: Serve yaml with a (non-standard) content-type There's no Standard from what I can tell, found this one somewhere. Serving as text/* might help some clients do something sensible like not treat it as a binary file, which it isn't.

---
summary: Log a message once per minute
...

This module sends `-- MARK --` to the log once per minute. This may be
useful to give a sense of how busy the server is or see that logging and
timers are still working.