cmd: improve wording of messages, spacing

Library/Homebrew/cmd/analytics.rb

Library/Homebrew/cmd/command.rb

Library/Homebrew/cmd/diy.rb

Library/Homebrew/cmd/info.rb

Library/Homebrew/cmd/install.rb

Library/Homebrew/cmd/link.rb

Library/Homebrew/cmd/missing.rb

Library/Homebrew/cmd/outdated.rb

Library/Homebrew/cmd/sh.rb

Library/Homebrew/cmd/tap-info.rb

Library/Homebrew/cmd/uninstall.rb

Library/Homebrew/cmd/untap.rb

Library/Homebrew/cmd/update.sh

Library/Homebrew/dev-cmd/bottle.rb

Library/Homebrew/dev-cmd/bump-formula-pr.rb

Library/Homebrew/dev-cmd/extract.rb

Library/Homebrew/dev-cmd/mirror.rb

Library/Homebrew/dev-cmd/pull.rb

Library/Homebrew/dev-cmd/tap-new.rb

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