If you say `placeholder: true` on a form element, Rails gets it from i18n. Do the same for `tooltip: true`

tooltipable.rb

# based on https://github.com/rails/rails/blob/master/actionview/lib/action_view/helpers/tags/placeholderable.rb
# config/initializers/tooltipable.rb

module ActionView
  module Helpers
    module Tags # :nodoc:
      module Tooltipable # :nodoc:
        def initialize(*)
          super

          if tag_value = @options[:tooltip]
            tooltip = tag_value if tag_value.is_a?(String)
            method_and_value = tag_value.is_a?(TrueClass) ? @method_name : "#{@method_name}.#{tag_value}"

            tooltip ||= Tags::Translator
              .new(object, @object_name, method_and_value, "helpers.tooltip")
              .translate
            tooltip ||= @method_name.humanize
            @options[:tooltip] = tooltip
          end
        end
      end
    end
  end
end

ActionView::Helpers::Tags::TextField.send(:include, ActionView::Helpers::Tags::Tooltipable)