bugfix

README.md

@@ -101,7 +101,7 @@ Todo
     - `void start_drawing(const float x, const float y)`:
 
       Signal that this object's drawing starts at coordinates (`x`, `y`) (typically the fingerdown location). 
-      The two arguments are both in $[-1, 1]$.
+      The two arguments are both in [-1, 1].
       Nothing is drawn by this function.
 
     - `bool draw(const float x, const float y, Toolbox& tb, bool drawing)`