Standardize links to wiki help pages.

* Fix inconsistencies in how wiki pages were linked.

* Link directly to the wiki instead of to a title search that is expected
  to redirect to the wiki.

app/views/wiki_pages/_secondary_links.html.erb

@@ -5,7 +5,7 @@
   <% if CurrentUser.is_member? %>
     <%= subnav_link_to "New", new_wiki_page_path %>
   <% end %>
-  <%= subnav_link_to "Help", wiki_pages_path(:search => {:title => "help:wiki"}) %>
+  <%= subnav_link_to "Help", wiki_page_path("help:wiki") %>
   <% if @wiki_page && @wiki_page.new_record? && @wiki_page.try(:tag).present? %>
     <li>|</li>
     <%= subnav_link_to "Posts (#{@wiki_page.tag.post_count})", posts_path(:tags => @wiki_page.title) %>