Update WhatsNew.txt

WhatsNew.txt

@@ -8,6 +8,7 @@ This is a list of major changes in SDL's version history.
 
 Android:
 * Removed SDL_HINT_ANDROID_SEPARATE_MOUSE_AND_TOUCH (replaced by SDL_HINT_MOUSE_TOUCH_EVENTS and SDL_HINT_TOUCH_MOUSE_EVENTS)
+  (Changed old default behavior from hardware mouse triggering touch events to now not doing so (SDL_MOUSE_TOUCH_EVENTS=0) to match the default behavior of other platforms")
 
 
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