Fix typo in idea for improvement 2.

Pretty sure "currently-selected" must be "currently selected".

Author: maxhumme

content/tutorial/tutorial.md

@@ -1091,7 +1091,7 @@ Check out the final result here: [Final Result](https://codepen.io/gaearon/pen/g
 If you have extra time or want to practice your new skills, here are some ideas for improvements you could make, listed in order of increasing difficulty:
 
 1. Display the move locations in the format "(1, 3)" instead of "6".
-2. Bold the currently-selected item in the move list.
+2. Bold the currently selected item in the move list.
 3. Rewrite Board to use two loops to make the squares instead of hardcoding them.
 4. Add a toggle button that lets you sort the moves in either ascending or descending order.
 5. When someone wins, highlight the three squares that caused the win.