Typo in README.barrier

I think there is a typo in src/backend/storage/lmgr/README.barrier.
Attached patch should fix it.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jpdiff --git a/src/backend/storage/lmgr/README.barrier
b/src/backend/storage/lmgr/README.barrier
index e73d6799ab..710ad2cca7 100644
--- a/src/backend/storage/lmgr/README.barrier
+++ b/src/backend/storage/lmgr/README.barrier
@@ -103,7 +103,7 @@ performed before the barrier, and vice-versa.
 
 Although this code will work, it is needlessly inefficient.  On systems with
 strong memory ordering (such as x86), the CPU never reorders loads with other
-loads, nor stores with other stores.  It can, however, allow a load to
+loads, nor stores with other stores.  It can, however, allow a load to be
 performed before a subsequent store.  To avoid emitting unnecessary memory
 instructions, we provide two additional primitives: pg_read_barrier(), and
 pg_write_barrier().  When a memory barrier is being used to separate two