Add number of services to product page

One of the user needs that we identified is not wanting to be the first
to use it. It feels like a much less risky choice if there are already
other people in government using it.

The easiest way to communicate this is with counts of how many services.
The count of departments is good because it shows breadth, where the
count of services shows depth.

Hard coded for now because we have no automatic way of splitting our
test services from real live services.

app/templates/views/signedout.html

@@ -95,6 +95,23 @@
       </div>
     </div>
   </div>
+  <div class="product-page-section">
+    <div class="with-keyline bottom-gutter-2">
+      <h2>Who’s using GOV.UK Notify</h2>
+      <div class="grid-row bottom-gutter">
+        <div class="column-half">
+          <h3 class="visually-hidden">Services</h3>
+          <div class="product-page-big-number">23</div>
+          services
+        </div>
+        <div class="column-half">
+          <h3 class="visually-hidden">Departments</h3>
+          <div class="product-page-big-number">14</div>
+          departments
+        </div>
+      </div>
+    </div>
+  </div>
   <div class="product-page-section">
     <div class="with-keyline bottom-gutter-2">
       <h2>Pricing</h2>