Fix paintCar example to include color as param

Author: ryanmcdermott

README.md

@@ -180,8 +180,8 @@ const Car = {
   carColor: "Blue"
 };
 
-function paintCar(car) {
-  car.carColor = "Red";
+function paintCar(car, color) {
+  car.carColor = color;
 }
 ```
 
@@ -194,8 +194,8 @@ const Car = {
   color: "Blue"
 };
 
-function paintCar(car) {
-  car.color = "Red";
+function paintCar(car, color) {
+  car.color = color;
 }
 ```