restore coment from the old index.html about overwriting the link selector

Author: lsylvester

actionview/test/ujs/src/attach-bindings.js

@@ -1,5 +1,8 @@
+// Must go before rails-ujs.
 document.addEventListener('rails:attachBindings', function() {
+  // This is for test in override.js.
   window.Rails.linkClickSelector += ', a[data-custom-remote-link]';
+
   // Hijacks link click before ujs binds any handlers
   // This is only used for ctrl-clicking test on remote links
   window.Rails.delegate(document, '#qunit-fixture a', 'click', function(e) {