Documentation: a few spelling fixes

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index bfbece9..0140c8e 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -91,7 +91,7 @@
 	combined by 'or'.
 
 --and | --or | --not | ( | )::
-	Specify how multiple patterns are combined using boolean
+	Specify how multiple patterns are combined using Boolean
 	expressions.  `--or` is the default operator.  `--and` has
 	higher precedence than `--or`.  `-e` has to be used for all
 	patterns.