SF #1547931, fix typo (missing and). Backport candidate for 2.3/2.4 too

Doc/ref/ref3.tex

@@ -762,7 +762,7 @@ user-defined method object whose associated class is the class
 (call it~\class{C}) of the instance for which the attribute reference
 was initiated or one of its bases,
 it is transformed into a bound user-defined method object whose
-\member{im_class} attribute is~\class{C} whose \member{im_self} attribute
+\member{im_class} attribute is~\class{C} and whose \member{im_self} attribute
 is the instance. Static method and class method objects are also
 transformed, as if they had been retrieved from class~\class{C};
 see above under ``Classes''. See section~\ref{descriptors} for