Rewrite runloop guide autorun FAQs

A rewrite of the autorun FAQs in the Runloop guide.

Fixes #1712 #1713 Partially addresses #1390
Apologies. More fat fingers.

> Without autoruns, there is a potential for race conditions to occur.

Should read

> With autoruns, there is a potential for race conditions to occur.

Autoruns themselves are not errors, but they may cause non-deterministic and unexpected behavior. They are a tradeoff- often they are good enough to avoid an error, but in a rare case they can cause errors themselves.

They are always less efficient.