Fix missing closing parenthesis in Input_Validation_Cheat_Sheet.md

The missing parenthesis has been added after matches()

cheatsheets/Input_Validation_Cheat_Sheet.md

@@ -105,7 +105,7 @@ private static final Pattern zipPattern = Pattern.compile("^\d{5}(-\d{4})?
 public void doPost( HttpServletRequest request, HttpServletResponse response) {
   try {
       String zipCode = request.getParameter( "zip" );
-      if ( !zipPattern.matcher( zipCode ).matches()  {
+      if ( !zipPattern.matcher( zipCode ).matches() ) {
           throw new YourValidationException( "Improper zipcode format." );
       }
       // do what you want here, after its been validated ..