Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "[release] fuel, armband: opnfv-7.1.0"
  - [release] fuel, armband: opnfv-7.1.0

    Change-Id: I005420665d569bb8f45aa3847509140a01c96e78
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index ac60400..728a30b 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit ac60400477b439a5cf8cdf77e990d2c0c8a75ab4
+Subproject commit 728a30b2f5f548d84af141620abb8b1a3b2d65d7