Add a note that divmod() with complex numbers is deprecated.

Doc/lib/libfuncs.tex

@@ -259,6 +259,9 @@ def my_import(name):
   \var{b} + \var{a} \%{} \var{b}} is very close to \var{a}, if
   \code{\var{a} \%{} \var{b}} is non-zero it has the same sign as
   \var{b}, and \code{0 <= abs(\var{a} \%{} \var{b}) < abs(\var{b})}.
+
+  \versionchanged[Using \function{divmod()} with complex numbers is
+                  deprecated]{2.3}
 \end{funcdesc}
 
 \begin{funcdesc}{enumerate}{iterable}