Fixed index references to modules. (This is *not* the spam module!)

Doc/lib/liboperator.tex

 % Contributed by Skip Montanaro, from the module's doc strings.
 
 \section{Built-in Module \sectcode{operator}}	% If implemented in C
-\bimodindex{spam}
+\bimodindex{operator}
 
 The \code{operator} module exports a set of functions implemented in C
 corresponding to the intrinsic operators of Python.  For example,

Doc/liboperator.tex

 % Contributed by Skip Montanaro, from the module's doc strings.
 
 \section{Built-in Module \sectcode{operator}}	% If implemented in C
-\bimodindex{spam}
+\bimodindex{operator}
 
 The \code{operator} module exports a set of functions implemented in C
 corresponding to the intrinsic operators of Python.  For example,