Add guide to create a proposal or investment

During a Participatory Budget, some users are getting confused and
creating a proposal instead of a budget investment. This intermediate
page should help them create investments

Adding a feature flag just in case other forks don’t need this feature
and setting seeds and dev_seeds for appropriate initial setup

app/controllers/guides_controller.rb

@@ -0,0 +1,8 @@
+class GuidesController < ApplicationController
+
+  skip_authorization_check
+
+  def new
+  end
+
+end