Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Fix release tagging script

    git cat-file can't output the tag information for a tag, but it can
    output the commit information a tag points to.

    Change-Id: I147941e2c0ba6defe212dbd0fc8c8a3a1fe0c728
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 91c0b5d..319f64d 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 91c0b5d520bdeab00af7feeed394b5112952a29e
+Subproject commit 319f64db7892a78ad70896a5571b46d332a30f99