Refine call-to-action styling in references upgrade dialog.

services/web/public/stylesheets/app/editor.less

@@ -255,7 +255,9 @@
 		.message {
 			margin-top: 15px;
 			text-align: center;
-			font-weight: bold;
+			&.call-to-action {
+				font-weight: bold;
+			}
 		}
 	}
 	.search-form {