Add hint about location (#50)

Author: edwardhorsford

app/views/reading/annotation.html

@@ -29,6 +29,9 @@ <h1 class="nhsuk-heading-l js-image-count">
       text: "Where in the breast is this annotation for?",
       classes: "nhsuk-label--s"
     },
+    hint: {
+      text: "For example, ‘Right upper outer quadrant’"
+    },
     id: "location",
     name: "location"
   }) }}