minor fix to doctag

Author: benholloway

lib/config/defaults.js

@@ -8,7 +8,7 @@ var instances = { };
 
 /**
  * Retrieve a instance of the multiton for the given key
- * @param {string} key The key for the mulititon
+ * @param {string} [key] The key for the multiton
  * @returns {{file: Function, defaults: Function, get: Function}}
  */
 function getInstance(key) {