Reword the add service page

Without the preview service name we probably have to go back to communicating
a bit more on the add service page. This commit brings back the two bullet
points about where the service name will appear, and tries to tie it into the
nice words that Matt Sheret wrote for us.

app/templates/views/add-service.html

@@ -16,16 +16,29 @@
     </h1>
 
     <p>
-      Be specific. Remember that there might be other people in your
-      organisation using GOV.UK Notify.
+      Be specific to your service. Remember that there might be
+      other people in your organisation using GOV.UK Notify.
     </p>
 
+    <p>
+      Users will see this:
+    </p>
+
+    <ul class="list-bullet bottom-gutter">
+      <li>
+        at the start of every text message, eg ‘Vehicle tax: we received your
+        payment, thank you’
+      </li>
+      <li>
+        as your email sender name
+      </li>
+    </ul>
+
     <form autocomplete="off" method="post">
 
       {{ textbox(form.name, hint="You can change this later") }}
 
-
-      {{ page_footer('Continue') }}
+      {{ page_footer('Add service') }}
 
     </form>