Update help text for job token setting

What does this MR do and why?

While reviewing a related MR, I spotted this help text that could be improved to be a bit clearer. You select projects (and groups of projects) here, you don't select individual job tokens, so this should be more accurate and easier to understand.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.