Add more examples to user guide

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Folks on Slack have agreed that some real-ish world examples would help.

I could glean some good stuff from past support questions. For example:

i’m considering using rewrite-clj to rewrite/rearrange my test suite. it’s currently written in the philosophy of “few deftests, many testing branches”, which makes running specific branches hard. i’m looking to pluck each testing branch out of the deftests and then place them in a new deftest with some name. would this be possible with rewrite-clj?

It almost feels like a Dear Abby column. Might be fun to structure like that.