Fix createIndex name option type

Author: perrin4869

lib/collection.js

@@ -1576,7 +1576,7 @@ define.classMethod('isCapped', {callback: true, promise:true});
  * @param {number} [options.max=null] For geospatial indexes set the high bound for the co-ordinates.
  * @param {number} [options.v=null] Specify the format version of the indexes.
  * @param {number} [options.expireAfterSeconds=null] Allows you to expire data on indexes applied to a data (MongoDB 2.2 or higher)
- * @param {number} [options.name=null] Override the autogenerated index name (useful if the resulting name is larger than 128 bytes)
+ * @param {string} [options.name=null] Override the autogenerated index name (useful if the resulting name is larger than 128 bytes)
  * @param {object} [options.partialFilterExpression=null] Creates a partial index based on the given filter object (MongoDB 3.2 or higher)
  * @param {object} [options.collation=null] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
  * @param {Collection~resultCallback} [callback] The command result callback