Better document wxAutomationObject::GetDispatchPtr() return value.

This function returns IDispatch pointer as a void one, mention that the user
code needs to upcast it itself.

Closes #12617.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65927 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/msw/ole/automtn.h

@@ -93,8 +93,11 @@ public:
 
     /**
         Gets the IDispatch pointer.
+
+        Notice that the return value of this function is an untyped pointer but
+        it can be safely cast to @c IDispatch.
     */
-    IDispatch* GetDispatchPtr() const;
+    void* GetDispatchPtr() const;
 
     /**
         Retrieves the current object associated with a class id, and attaches the