doc: trivial typo in git-format-patch.txt

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index bdeecd5..9c5f832 100644
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -551,7 +551,7 @@
 ................................................
 
 With `git format-patch --base=P -3 C` (or variants thereof, e.g. with
-`--cover-letter` of using `Z..C` instead of `-3 C` to specify the
+`--cover-letter` or using `Z..C` instead of `-3 C` to specify the
 range), the base tree information block is shown at the end of the
 first message the command outputs (either the first patch, or the
 cover letter), like this: