Should coqbot respond with a 😕 on comments which mention (tag?) @coqbot but don't trigger any action?

[JasonGross]

This might make it easier to know whether the issue is a problem with coqbot seeing the comment at all vs coqbot parsing the comment. (This idea came up after @dependabot thumbs-uped my request to rebase.)

[Zimmi48]

Sounds reasonable, although we could even respond to comments which coqbot doesn't understand with a summary of what coqbot can be triggered to do similar to command-line tools printing the help message when the provided arguments are wrong (see #106).