Shows the assignment note in moderator post.

Note there were no migrations to retroactively add the notes into small action posts

• A small action post generated from assignment has no relation to its topic/post
  • its PostCustomFields used in assign are used elsewhere as well (e.g. action_code_who etc)
• Vice versa, an assignment does not have relationship to its generated small action post

Each note modification also adds a moderator post, rather than modify the previous post. If we wish to have that, it's possible too.