Add "Tech review not needed" label

[apinnick]

I think it would be useful to create a "Tech review not needed" label for PRs that fix only style issues.

[maximiliankolb]

I did some cleanup and deleted unused labels. current list: https://github.com/theforeman/foreman-documentation/issues/labels

alternative to "tech review not needed": use "tech review done".

[apinnick]

The problem with that is that people assume "tech review done" means tech review was done. A PR was marked 'tech review done' when it did not need tech review. However, it turned out that the PR should have gone through tech review.

Labels that are not precise cause confusion. That is why I am proposing this label. For that matter, I think "Style review not needed" would also be a good idea.