Fix typo

Doc/lib/libitertools.tex

@@ -354,7 +354,7 @@ by functions or loops that truncate the stream.
 
   Note, this member of the toolkit may require significant auxiliary
   storage (depending on how much temporary data needs to be stored).
-  In general, if one iterator is going use most or all of the data before
+  In general, if one iterator is going to use most or all of the data before
   the other iterator, it is faster to use \function{list()} instead of
   \function{tee()}.
   \versionadded{2.4}