RelNotes/2.21.1: typofix

Signed-off-by: NMartin Ågren <martin.agren@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/RelNotes/2.22.1.txt

@@ -94,7 +94,7 @@ Fixes since v2.22
 
  * The configuration variable rebase.rescheduleFailedExec should be
    effective only while running an interactive rebase and should not
-   affect anything when running an non-interactive one, which was not
+   affect anything when running a non-interactive one, which was not
    the case.  This has been corrected.
 
  * "git submodule foreach" did not protect command line options passed