Add api docs landing content

packages/node_modules/node-red/lib/red.js

@@ -39,6 +39,9 @@ function checkVersion(userSettings) {
  * This module provides the full Node-RED application, with both the runtime
  * and editor components built in.
  *
+ * The API this module exposes allows it to be embedded within another node.js
+ * application.
+ *
  * @namespace node-red
  */
 module.exports = {
@@ -125,7 +128,11 @@ module.exports = {
 
     /**
      * This provides access to the internal nodes module of the
-     * runtime.
+     * runtime. The details of this API remain undocumented as they should not
+     * be used directly.
+     *
+     * Most administrative actions should be performed use the runtime api
+     * under [node-red.runtime]{@link node-red.runtime}.
      *
      * @memberof node-red
      */