docs(collection): document ordered option for insertMany

As specified in https://github.com/mongodb/specifications/blob/master/source/crud/crud.rst#basic

lib/collection.js

@@ -478,6 +478,7 @@ define.classMethod('insertOne', {callback: true, promise:true});
  * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
  * @param {boolean} [options.forceServerObjectId=false] Force server to assign _id values instead of driver.
  * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {boolean} [options.ordered=true] If true, when an insert fails, don't execute the remaining writes. If false, continue with remaining inserts when one fails.
  * @param {Collection~insertWriteOpCallback} [callback] The command result callback
  * @return {Promise} returns Promise if no callback passed
  */