Add document title to promotion report

app/views/reports/user_promotions.html.erb

@@ -35,6 +35,10 @@
   </div>
 </div>
 
+<% content_for(:page_title) do %>
+  User Promotion Report - <%= Danbooru.config.app_name %>
+<% end %>
+
 <%= content_for(:html_header) do %>
   <%= javascript_include_tag "stupidtable" %>
   <script type="text/javascript">