How do I install these formulae?
brew tap homebrew/completions and then
brew install <formula>.
If the formula conflicts with one from Homebrew/homebrew or another tap, you can
brew install homebrew/completions/<formula>.
You can also install via URL:
brew install https://raw.githubusercontent.com/Homebrew/homebrew-completions/master/<formula>.rb
man brew, or the Homebrew wiki.