Fix grammar nits in documentation and in code comments.

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin-blame.c b/builtin-blame.c
index d98caaf..9b4c02e 100644
--- a/builtin-blame.c
+++ b/builtin-blame.c
@@ -606,7 +606,7 @@
 
 /*
  * src typically is on-stack; we want to copy the information in it to
- * an malloced blame_entry that is already on the linked list of the
+ * a malloced blame_entry that is already on the linked list of the
  * scoreboard.  The origin of dst loses a refcnt while the origin of src
  * gains one.
  */