Fix ascii art blocks.

svn path=/plone.app.discussion/trunk/; revision=37336

plone/app/discussion/design.txt

@@ -52,6 +52,8 @@ The inheritance tree for DiscussionItem is shown below. Classes we want to
 mix in and interface we want to implement in the Comment class are marked
 with [x].
 
+::
+
     [ ] DiscussionItem
         [ ] Document
             [ ] PortalContent                       = [ ] IContentish
@@ -126,6 +128,8 @@ could manage the 'Bypass moderation' permission.
 
 These could work in a workflow like this:
 
+::
+
   * --> [posted] -- {publish} --> [published]--> *
            |                          ^
            |                          |