GA changes to docs for Agent

[NickJosevski]

I took the questions and answers from communit slack to create this FAQ at the end of the trouble shooting page.

I opt'd for keeping the question part vague similar to how customers asked it in slack, so more people consider that a specific issue may be what they're experiencing.

The slack messages will slowly be less accessible to us, as there's a rolling window of what we can see (maybe 90 days of history in community slack).

[steve-fenton-octopus]

@NickJosevski this PR has been inactive for over 6 months. Do you want to persist with this change? If so, there's a merge conflict to resolve.