Cleanup the manpage section on dealing with failed tests
Cleanup the manpage section on dealing with failed tests

This commit address some issues in the docs section about dealing with
failed tests. There were some formatting issues, as well as just factual
mistakes on how the commands work. This tries to address those to make
it easier to read.

mtreinish/stestr,masayukig/stestr,mtreinish/stestr,masayukig/stestr