dev-cmd/update-maintainers: If there are changes, auto-update man pages

- I noticed this in a PR recently, maybe the maintainer didn't think
  they would have to run `brew man` for this? In that case there's an
  extra step after the PR is raised, red CI checks on the PR (which is
  demoralising) and potentially requires a reviewer to point this out.
- This runs `brew man` if the `README` file has a diff as part of this
  command. Then the user has to `git add .` and their PR is (probably)
  good.

Library/Homebrew/dev-cmd/update-maintainers.rb

@@ -3,6 +3,7 @@
 
 require "cli/parser"
 require "utils/github"
+require "dev-cmd/man"
 
 module Homebrew
   extend T::Sig
@@ -61,7 +62,8 @@ module Homebrew
     if diff.status.success?
       puts "No changes to list of maintainers."
     else
-      puts "List of maintainers updated in README."
+      Homebrew.regenerate_man_pages(preserve_date: true, quiet: true)
+      puts "List of maintainers updated in the README and the generated man pages."
     end
   end
 end