This flag allows a full text search on man pages. Although this is a last resort
option, it can be useful to pin point a certain man page.
It can be used with -S to narrow the search.
Unlike the Linux version, the search takes place in the rendered text so it
avoids false-positives when the text is found in comments in the source files.
It relies on `grep(1)` and `mandoc(1)` to do its job.
Add flag documentation and EXAMPLES to the manual page (bump .Dd).
Usage example:
man -w -K '\<arm\>' -S 1:8
Reviewed By: ceri, emaste, pauamma_gundo.com
Approved by: manpages (bcr@), debdrup@
Differential Revision: https://reviews.freebsd.org/D30984
1594084f3f