Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Disable undercloud as containers for now

    Upstream has moved to install undercloud as containers which breaks our
    post undercloud configuration for some services. Disable it for now and
    then move to it gracefully in a future patch.

    Change-Id: I0cd1a8ddac4ba92734750265d2a16d3ef008f236
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 1e43a5e..6f7a9a9 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 1e43a5eaa2c5c61110c871e85f20b1f73ad361f0
+Subproject commit 6f7a9a9441e6ce5b689a0c5705804d8eea0e002a