code: def gen_usage
        puts 'Usage:'
        puts '  poole [ACTION] [ARG]'
        puts ''
        puts 'Actions:'
        puts '  draft      Create a new draft in _drafts with title SLUG'
        puts '  post       Create a new timestamped post in _posts with title SLUG'
        puts '  publish    Publish the draft with SLUG, timestamping appropriately'
        puts '  unpublish  Move a post to _drafts, untimestamping appropriately'
        exit
      end
docs: Print a usage message and exit