Automatically add .github directory to .Rbuildignore

[Hezi Buba]

First of all, many thanks for the package - new version works well and I love the use of github actions.

I've encountered the following NOTE using rhub::rhub_check():

Found the following hidden files and directories:
  .github
These were most likely included in error. See section 'Package
structure' in the 'Writing R Extensions' manual.

CRAN-pack does not know about
  .github

Adding .github to .Rbuildignore eliminates this NOTE.
I was wondering if rhub::rhub_setup() should automatically add .github to .Rbuildignore or throw a message in the console to do so prior to using rhub::rhub_check() in case it is not added yet.

Thanks

[Gábor Csárdi]

Thanks for the feedback, I guess rhub_check() or rhub_doctor() could give you a hint.

OTOH you'll probably get the same note if you run R CMD check locally, so maybe people will see it early?

[Hezi Buba]

I ran R CMD check immediately before and didn't think twice and did rhub_setup() -> rhub_doctor() -> rhub_check()

Either way, this issue will serve as a reference when people will encounter this note locally.