Update README

Author: ra1028

README.md

@@ -431,6 +431,10 @@ XCTAssertEqual(tester.value.count, 0)
 
 tester.value.increment()
 
+XCTAssertEqual(tester.value.count, 1)
+
+tester.update()  // Simulates view's update.
+
 XCTAssertEqual(tester.value.count, 1)
 ```