SetStatus docs proofreading and 'apropriate' typos

[NReilingh]

I initially just noticed the "scheam" typo in SetStatus.pm and was just going to submit that, but then I noticed that the rest of the docs in the same module could use an edit pass for clarity, spelling, and grammar.

I also noticed that "apropriate" was misspelled in a few other places, so I searched it in the codebase and corrected the other user-facing instances.