Fix formatting typo in Misc/NEWS.

Misc/NEWS

@@ -104,7 +104,7 @@ Library
   selection or control(command) '-' or '+' or control-mousewheel.
   Original patch by Lita Cho.
 
-_ Issue #21597: The separator between the turtledemo text pane and the drawing
+- Issue #21597: The separator between the turtledemo text pane and the drawing
   canvas can now be grabbed and dragged with a mouse.  The code text pane can
   be widened to easily view or copy the full width of the text.  The canvas
   can be widened on small screens.  Original patches by Jan Kanis and Lita Cho.