Merge in v5 code

scripts/docs/dgeni/processors/hide-private-api.js

@@ -0,0 +1,9 @@
+"use strict";
+module.exports = function removePrivateApi() {
+  return {
+    name: 'remove-private-api',
+    description: 'Prevent the private apis from being rendered',
+    $runBefore: ['rendering-docs'],
+    $process: docs => docs.filter(doc => !doc.private && (!doc.tags || !doc.tags.tagsByName.get('hidden')))
+  };
+};