Add Documenter key and warning about SSH setup

[gdalle]

Fix #459

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6f6c392) 94.33% compared to head (34f4eea) 94.33%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #460   +/-   ##
=======================================
  Coverage   94.33%   94.33%           
=======================================
  Files          24       24           
  Lines         742      742           
=======================================
  Hits          700      700           
  Misses         42       42           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[oxinabox]

I wish we could automate this step

[gdalle]

Me too, but I'm not sure we can fiddle with the GitHub API, especially with secret SSH keys, and live to tell the tale

[adrhill]

I wish we could automate this step

Maybe a solution between just having a note in the docstring and calling the GitHub API would be to print the output of DocumenterTools.genkeys from PkgTemplates?

[gdalle]

It would have to be printed at the very end though cause there's lots of output. But it's a good idea, maybe open an issue to keep track?