Eliminate unnecessary deploys and noise from help site PRs

[roryabraham]

Problem

When help site PRs are merged, they are subjected to the same CI/CD as the rest of the repo. This means that they:

1. May trigger NewDot deploys
2. Will get inaccurate/misleading deploy comments
3. Will cause unnecessary noise in GitHub and slack

Why this is important

It will be a distraction and waste people's time. It's also just annoying

Solution

Skip most NewDot CI/CD if a merged PR only changes files under the /docs directory.

[roryabraham]

Going to close this in favor of #9725