Update state-and-lifecycle.md (#496)

content/docs/state-and-lifecycle.md

@@ -317,7 +317,7 @@ Let's quickly recap what's going on and the order in which the methods are calle
 
 3) When the `Clock` output is inserted in the DOM, React calls the `componentDidMount()` lifecycle hook. Inside it, the `Clock` component asks the browser to set up a timer to call the component's `tick()` method once a second.
 
-4) Every second the browser calls the `tick()` method. Inside it, the `Clock` component schedules a UI update by calling `setState()` with an object containing the current time. Thanks to the `setState()` call, React knows the state has changed, and calls `render()` method again to learn what should be on the screen. This time, `this.state.date` in the `render()` method will be different, and so the render output will include the updated time. React updates the DOM accordingly.
+4) Every second the browser calls the `tick()` method. Inside it, the `Clock` component schedules a UI update by calling `setState()` with an object containing the current time. Thanks to the `setState()` call, React knows the state has changed, and calls the `render()` method again to learn what should be on the screen. This time, `this.state.date` in the `render()` method will be different, and so the render output will include the updated time. React updates the DOM accordingly.
 
 5) If the `Clock` component is ever removed from the DOM, React calls the `componentWillUnmount()` lifecycle hook so the timer is stopped.