Stop lying about [].pop() being experimental! There is no backing it out

at this point.

Doc/lib/libstdtypes.tex

@@ -506,10 +506,9 @@ Notes:
 \item[(3)] Raises \exception{ValueError} when \var{x} is not found in
   \var{s}.
 
-\item[(4)] The \method{pop()} method is experimental and at the moment
-  only supported by the list and array types.  The optional argument
-  \var{i} defaults to \code{-1}, so that by default the last item is
-  removed and returned.
+\item[(4)] The \method{pop()} method only supported by the list and
+  array types.  The optional argument \var{i} defaults to \code{-1},
+  so that by default the last item is removed and returned.
 
 \item[(5)] The \method{sort()} and \method{reverse()} methods modify the
   list in place for economy of space when sorting or reversing a large