Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Updated Docs Structure"
  - Updated Docs Structure

    Provides a new organizational structure for release engineering
    documentation:

     /ci           | Job/Gate structures and CI requirements
     /infra        | Software Infrastructure documentation
       /component  | Documentation specific to a component (Gerrit, etc.)
     /release      | Release documentation (ex. stable branch policy)

    Change-Id: I8d24435d4d2f5ab797ad90309ee2246fb9b74c8e
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a56fe00..39596fd 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a56fe00d0d5c962de8034b15c24b3d8310ed195e
+Subproject commit 39596fd4bb2457fa20d14ca0cdf4537122340054