man: omit global options from shell command usage

When reading the comment header of a shell command, omit options that
are in Homebrew::CLI::Parser.global_options, since they are documented
separately for all commands.

Library/Homebrew/dev-cmd/man.rb

@@ -195,6 +195,9 @@ module Homebrew
       line = line.slice(4..-1)
       next unless line
 
+      # Omit the common global_options documented separately in the man page.
+      next if line =~ /--(debug|force|help|quiet|verbose) /
+
       # Format one option or a comma-separated pair of short and long options.
       lines << line.gsub(/^ +(-+[a-z-]+), (-+[a-z-]+) +/, "* `\\1`, `\\2`:\n  ")
                    .gsub(/^ +(-+[a-z-]+) +/, "* `\\1`:\n  ")

docs/Manpage.md

@@ -540,9 +540,6 @@ Fetch the newest version of Homebrew and all formulae from GitHub using `git`(1)
 * `--merge`:
   `git merge` is used to include updates (rather than `git rebase`).
 
-* `--force`:
-  Always do a slower, full update check (even if unnecessary).
-
 ### `update-reset` [*`repository`*]
 Fetches and resets Homebrew and all tap repositories (or any specified `repository`) using `git`(1) to their latest `origin/master`. Note this will destroy all your uncommitted or committed changes.
 

manpages/brew.1

@@ -660,10 +660,6 @@ Fetch the newest version of Homebrew and all formulae from GitHub using \fBgit\f
 \fB\-\-merge\fR
 \fBgit merge\fR is used to include updates (rather than \fBgit rebase\fR)\.
 .
-.TP
-\fB\-\-force\fR
-Always do a slower, full update check (even if unnecessary)\.
-.
 .SS "\fBupdate\-reset\fR [\fIrepository\fR]"
 Fetches and resets Homebrew and all tap repositories (or any specified \fBrepository\fR) using \fBgit\fR(1) to their latest \fBorigin/master\fR\. Note this will destroy all your uncommitted or committed changes\.
 .