Add padding to bottom of wiki page, fix #12921.

app/views/projects/wikis/show.html.haml

@@ -18,7 +18,7 @@
     You can view the #{link_to "most recent version", namespace_project_wiki_path(@project.namespace, @project, @page)} or browse the #{link_to "history", namespace_project_wiki_history_path(@project.namespace, @project, @page)}.
 
 
-.wiki-holder.prepend-top-default
+.wiki-holder.prepend-top-default.append-bottom-default
   .wiki
     = preserve do
       = render_wiki_content(@page)