Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Fetch mistral logs from undercloud

    /var/lib/mistral path contains logs for when ansible is invoked by
    TripleO for Ceph configuration as well as config download. This patch
    now archives and fetches that directory. Logs in previous releases
    like Queens store the Ceph logs in /var/log/mistral.

    Change-Id: I50c43e55efaa5dbcf8b7fb00b0e11cd3288fdd05
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 83ef5ed..8dc27bd 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 83ef5ed70381583e1a419716cd9acbf9538074c6
+Subproject commit 8dc27bd1443a52c177e6dedf550fd7d24a81e84e