Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 52fe2bfcad5ce039fc8e512343d12a085a074e1f
  - Merge "Add debugs when calling gsutil"
  - Add debugs when calling gsutil

    Change-Id: I8e0618e344ade4eb692a15eab1eecfa0d479ba6f
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 3abf685..52fe2bf 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 3abf6852a28a2f11c7c893a93822e8132fb46f9e
+Subproject commit 52fe2bfcad5ce039fc8e512343d12a085a074e1f