Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Merge "Updating the iso build to CentOS 7.4"
  - Updating the iso build to CentOS 7.4

    JIRA: APEX-522

    Change-Id: I03efc6ccad708d12f3fdabd9ace9935edb31d4bb
    Signed-off-by: Dan Radez <dradez@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 864527c..ca0196f 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 864527cb7a61eda541aa812fe985843989595e9a
+Subproject commit ca0196f2e216eb25d9acfce4379f8530834736e8