Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "prototypes: bifrost: Write clouds.yaml file for regular users"
  - prototypes: bifrost: Write clouds.yaml file for regular users

    This is similar to commit 6769ae9bcbf6 ("prototypes: bifrost: Add
    keystone roles"). In preparation for running the bifrost jobs as normal
    user we need to write a clouds.yaml file to users home directory.
    This is similar to the bifrost upstream testing playbook.

    Change-Id: Iae4bc73906649707667925280a19282ec5c93998

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a495738..5810ec4 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a495738171484faa8248bb6c12cfde0c1d123ff3
+Subproject commit 5810ec4eaa3bddf165f255fd222f864712c5d34f