brew.rb: fix help regex.
brew.rb: fix help regex.

Don't match `help` at the end of every string because `brew installhelp`
shouldn't really be running help.

Closes Homebrew/homebrew#36559.
Closes Homebrew/homebrew#36576.

Signed-off-by: Mike McQuaid <a17fed27eaa842282862ff7c1b9c8395a26ac320@mikemcquaid.com>

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