Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Apex: Fix OS branch detection on snapshot promotion

    Change-Id: I4f860f9b9adcc96d94b1daa333eec7a746bc91b1
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 0af8cbd..4191a7f 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 0af8cbde5adf37aaa481bf826afd7069893d99f3
+Subproject commit 4191a7f162fb41f7933fb0a205c5a33d66ad8e21