rubocop: turn off Rails/ContentTag
rubocop: turn off Rails/ContentTag

This cop suggests (and even autocorrects!) an instance of:

  tag("img", options)

to change into:

  tag.img(options)

But as discussed in https://github.com/git/git-scm.com/pull/1742,
this actually breaks the call!

I'm still puzzled about why this is. But I find that I don't care enough
to investigate deeply, and it would be useful to have CI on "main"
actually pass, so unrelated pull requests aren't confused into thinking
they broke something. So let's just disable the cop for now.

git/git-scm.com,git/git-scm.com,git/git-scm.com,git/git-scm.com