SF patch #834444: add versionadd to new functions

(Contributed by George Yoshida.)

Doc/lib/liboperator.tex

@@ -66,10 +66,12 @@ constructor.
 
 \begin{funcdesc}{is_}{a, b}
 Return \code{\var{a} is \var{b}}.  Tests object identity.
+\versionadded{2.3}
 \end{funcdesc}
 
 \begin{funcdesc}{is_not}{a, b}
 Return \code{\var{a} is not \var{b}}.  Tests object identity.
+\versionadded{2.3}
 \end{funcdesc}