Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Fixes delorean repo update on undercloud

    Previous fix to update delorean repo on undercloud was always failing
    because the operations passed to virt-customize were not in a list type.

    JIRA: APEX-565

    Change-Id: Ic883309ac1c3aa6027dc252635e404e5355c269d
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index c8f07fd..3812d09 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit c8f07fda6445b9b3b1fcb9d97f05cd40fffe8daf
+Subproject commit 3812d0987d078a8a0ad93724e8188994b7579e50