Manual updates.

For literal strings, we need to use \- instead of just - as some troff
processors turn plain "-" into "proper" unicode hyphens (as opposed to
hyphen-minus), which breaks copy+paste and searching.

Ensure that .Os follows .Dt in the mdoc prologue as apparently not doing
this results in broken manpage headings with groff 1.23.

Add missing copyright and permission notice.