Removed unnecessary dot. (#494)

content/tutorial/tutorial.md

@@ -1053,7 +1053,7 @@ Add a method called `jumpTo` to the Game class:
   }
 ```
 
-Then update `stepNumber` when a new move is made by adding `stepNumber: history.length` to the state update in Game's `handleClick`. We'll also update `handleClick` to be aware of `stepNumber` when reading the current board state so that you can go back in time then click in the board to create a new entry.:
+Then update `stepNumber` when a new move is made by adding `stepNumber: history.length` to the state update in Game's `handleClick`. We'll also update `handleClick` to be aware of `stepNumber` when reading the current board state so that you can go back in time then click in the board to create a new entry:
 
 ```javascript{2,13}
   handleClick(i) {