Add coverage configuration

[chillenzer]

I would consider configuration for coverage beneficial (at least to know about it). My standard approach (in projects from scratch or when it is a manageable effort) is to aim for 100% coverage and explicitly and consciously exclude parts that do not need testing, e.g., the small main function. That is, I believe, a much healthier approach to code coverage than just monitoring its slow decay or trying to hit a target threshold but in that pursuit only covering unimportant lines.

[edbennett]

Worth mentioning, certainly. I wouldn't currently prioritise writing a full section on how to do it, however.