Merge pull request #2081 from alphagov/page-break-guidance

Add guidance on how to use page breaks in letters

app/templates/partials/templates/guidance-formatting-letters.html

@@ -17,3 +17,15 @@
     * point 3<br/>
   </p>
 </div>
+<p>
+  To insert a page break, use three asterisks:
+</p>
+<div class="panel panel-border-wide">
+  <p>
+    Content on page 1<br/>
+    <br/>
+    ***<br/>
+    <br/>
+    Content on page 2<br/>
+  </p>
+</div>