Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "[fuel] Handle os cacert for alpine as well"
  - [fuel] Handle os cacert for alpine as well

    Change-Id: Ie7e8228dc4316a70c8cd800415108180148f5f31
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a8892f9..6b30c00 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a8892f93aa56e56fb6cf3bcfc7ca208485095958
+Subproject commit 6b30c00a481d452d1b9ee4468054ce59e631f19a