fixed miss-named link to knockout reference

knockout.validation/knockout.validation.d.ts

@@ -3,7 +3,7 @@
 // Definitions by: Dan Ludwig <https://github.com/danludwig>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 
-/// <reference path="../knockouot/knockout.d.ts" />
+/// <reference path="../knockout/knockout.d.ts" />
 
 interface KnockoutValidationGroupingOptions {
     deep?: bool;