tutorial: grammofix

We say "these", so "range notations" must be plural.

Reported-by: Furkan Akkurt
Signed-off-by: Junio C Hamano <[email protected]>

Author: gitster

Documentation/gittutorial.txt

@@ -361,7 +361,7 @@ $ gitk HEAD...FETCH_HEAD
 This means "show everything that is reachable from either one, but
 exclude anything that is reachable from both of them".
 
-Please note that these range notation can be used with both gitk
+Please note that these range notations can be used with both gitk
 and "git log".
 
 After inspecting what Bob did, if there is nothing urgent, Alice may