Update reference missed out in previous commit

Author: pyitphyoaung

docs/tutorial/tutorial.md

@@ -936,7 +936,7 @@ Let's show the previous moves made in the game so far. We learned earlier that R
 
 [View the current code.](https://codepen.io/gaearon/pen/EmmGEa?editors=0010)
 
-For each step in the history, we create a list item `<li>` with a button `<a>` inside it that has a click handler which we'll implement shortly. With this code, you should see a list of the moves that have been made in the game, along with a warning that says:
+For each step in the history, we create a list item `<li>` with a button `<button>` inside it that has a click handler which we'll implement shortly. With this code, you should see a list of the moves that have been made in the game, along with a warning that says:
 
 >  Warning:
 >  Each child in an array or iterator should have a unique "key" prop. Check the render method of "Game".