Documentation: minor grammatical fixes in git-blame.txt.

Signed-off-by: David J. Mellor <dmellor@whistlingcat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/blame-options.txt b/Documentation/blame-options.txt
index df2a7c1..26cfb62 100644
--- a/Documentation/blame-options.txt
+++ b/Documentation/blame-options.txt
@@ -39,7 +39,7 @@
 	Show raw timestamp (Default: off).
 
 -S <revs-file>::
-	Use revs from revs-file instead of calling linkgit:git-rev-list[1].
+	Use revisions from revs-file instead of calling linkgit:git-rev-list[1].
 
 --reverse::
 	Walk history forward instead of backward. Instead of showing