Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Switch from block-level to blocking-level (former)"
  - Switch from block-level to blocking-level (former)

    [1] https://docs.openstack.org/infra/jenkins-job-builder/properties.html

    Change-Id: Ic9e20f28ab3093ff29c1cc1681e75812db7ed949
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 9137020..8f5681b 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 913702029da101bd40484c03171429060a4ec35e
+Subproject commit 8f5681b3e80bb7033224d4fdeeb751b52082d62f