config: document profiling.show{min,max}

check-config: look for ui.configwith We previously weren't looking for this config helper. And, surprise, profiling.py references config options without docs. If I tried hard enough, I could have combined the regexps using a positive lookbehind assertion or something. But I didn't want to make my brain explode. At some point, we should probably do this linting at the tokenizer or ast layer. I'm not willing to open that can of worms right now.

check-config: use named groups in regexp In preparation for making this regexp a bit more complicated.