A variety of mdoc(7) and grammar changes:
* use .Bl and .El directives when using a list
* use .Dv directive when appropriate
* use 'The' to start a sentence instead of the function name
* paragraph cleanups for return values
* use approrpriate directives to markup pointers and types
* use .Er directive for marking up errno(3) values
* eliminate hard sentence breaks
* use .Dv instead of .Va when documenting known constants
* eliminate empty lines
* spelling and grammar corrections
* eliminate incorrect use of the .Lb directive
While I am here, add a reference to the rfork(2) manual page
under the SEE ALSO section.