deheader: update to 1.1, make HEAD-related changes
The old HEAD location is Gitorious, which says it's shutting down at the
end of May.
In attempting to build HEAD, I found that some DocBook files were
necessary, but I can't find them anywhere in Homebrew. So the man page
installation is skipped for `--HEAD`.
ClosesHomebrew/homebrew#39180.
Signed-off-by: Tim D. Smith <git@tim-smith.us>
