man: cleanup and update manual page #4121
@jonathangray : Thanks for the improvements to the ScummVM Manual page.
One minor point, could you rebase and edit these commits to change the prefix from "man: ..." to "DOC: MAN: ..." or similar as per https://wiki.scummvm.org/index.php?title=Commit_Guidelines#Commit_message_formatting
If you don't know how to do this or don't feel able to, I or another of the team should be able to do this to the PR (since team members have permissions to edit the PR branches).
avoids mandoc warnings of the form STYLE: no blank before trailing delimiter: Fl n,