Make no assumption about how modules are built when referring to them; this

can vary by platform and installation.
Based on suggestion to python-docs.

Doc/lib/libstdtypes.tex

@@ -791,10 +791,9 @@ are replaced by \code{\%g} conversions.\footnote{
   point values on a particular machine.
 }  All other errors raise exceptions.
 
-Additional string operations are defined in standard module
-\refmodule{string} and in built-in module \refmodule{re}.
-\refstmodindex{string}
-\refstmodindex{re}
+Additional string operations are defined in standard modules
+\refmodule{string}\refstmodindex{string} and
+\refmodule{re}.\refstmodindex{re} 
 
 
 \subsubsection{XRange Type \label{typesseq-xrange}}