More robust checking on the About screen of the GraphQL rate limit in…

…formation being nil

webapp/views/about.erb

@@ -11,7 +11,13 @@
   </ul>
 </nav>
 
-<p><%= rate_limit.class %></p>
+<% unless rate_limit.is_a?(NilClass) || rate_limit.nil? %>
+<section id="rate-limit">
+  <h3>GitHub GraphQL API Rate Limit</h3>
+  <p><%=pluralise(rate_limit.remaining, 'point', 'points') %> remaining out of <%=pluralise(rate_limit.limit, 'point', 'points') %> limit</p>
+  <p>Resets <%=d rate_limit.reset_at %></p>
+</section>
+<% end %>
 <section id="version-info">
   <h3>Version Information</h3>
   <p>Branch: <a href="https://github.com/ONSdigital/<%=h repo_name%>/tree/<%=h branch %>"><%=h branch %></a></p>