Add documentation for CURRENCY and SCODE wxVariant classes.

This should have been part of r72081.

See #14225.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72083 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/variant.h

@@ -26,6 +26,10 @@
     the wxVariantData object, unlike the case for basic data types where
     convenience functions such as GetLong() can be used.
 
+    Under Microsoft Windows, two additional wxVariantData-derived classes --
+    wxVariantDataCurrency and wxVariantDataErrorCode -- are available for
+    interoperation with OLE VARIANT when using wxAutomationObject.
+
     Pointers to any wxObject derived class can also easily be stored in a
     wxVariant. wxVariant will then use wxWidgets' built-in RTTI system to set
     the type name  (returned by GetType()) and to perform type-safety checks at