Reword the help text about adding placeholders

In research we’ve seen users struggle with this. Often they’d type
((Joe Bloggs)) or ((XX/XX/XXXX)) instead of a sensible name.

Lets see if explaining it differently helps.

app/assets/stylesheets/views/edit-template.scss

@@ -3,7 +3,7 @@
   &-placeholder-hint {
     display: block;
     padding-top: 20px;
-    color: $secondary-text-colour;
+    //color: $secondary-text-colour;
   }
 
 }