Fix the `doc` command for users of BSD `man`
Fix the `doc` command for users of BSD `man`

This commit uses options and flags that will work on both the BSD and
the `man-db` implementations, however those changes remain unportable as
the POSIX standard only defines a single `-k` flag for the utility,
which we don't need.

The call to the `col` utility has also been replaced by a call to `sed`,
as the former is only shipped on systems that have the `nroff` formatter
installed.

Somasis/kakoune,ekie/kakoune,occivink/kakoune,danr/kakoune,flavius/kakoune,flavius/kakoune,jjthrash/kakoune,mawww/kakoune,mawww/kakoune,jkonecny12/kakoune,Somasis/kakoune,casimir/kakoune,ekie/kakoune,flavius/kakoune,ekie/kakoune,ekie/kakoune,mawww/kakoune,alexherbo2/kakoune,alexherbo2/kakoune,lenormf/kakoune,alexherbo2/kakoune,casimir/kakoune,casimir/kakoune,occivink/kakoune,mawww/kakoune,jjthrash/kakoune,flavius/kakoune,lenormf/kakoune,jjthrash/kakoune,alexherbo2/kakoune,jjthrash/kakoune,occivink/kakoune,jkonecny12/kakoune,lenormf/kakoune,Somasis/kakoune,jkonecny12/kakoune,Somasis/kakoune,casimir/kakoune,lenormf/kakoune,danr/kakoune,jkonecny12/kakoune,occivink/kakoune,danr/kakoune,danr/kakoune