Restore accidentally removed EVT_GRID_CMD_RANGE_SELECT macro

This was removed in 415f080c80 (Split wxGrid RANGE_SELECT event into
SELECTING and SELECTED, 2020-07-27) without preserving it for
compatibility. Do define it now, just as it was done for the non-CMD
equivalent of this macro EVT_GRID_RANGE_SELECT.

Also update the documentation to fix a typo from e2f316b19d (Mention
that wxEVT_GRID_RANGE_SELECT{ED,ING} are new in 3.1.5, 2020-08-18).

interface/wx/grid.h

@@ -6398,7 +6398,7 @@ public:
         The user selected a group of contiguous cells; variant taking a window
         identifier. Processes a @c wxEVT_GRID_RANGE_SELECTED event type.
         This event is available in wxWidgets 3.1.5 and later only and was
-        called @c wxEVT_GRID_RANGE_SELECT in the previous versions.
+        called @c wxEVT_GRID_CMD_RANGE_SELECT in the previous versions.
     @endEventTable
 
     @library{wxcore}