Update git submodules

* Update docs/submodules/apex from branch 'stable/euphrates'
  - Merge "Updates to Inventory object" into stable/euphrates
  - Updates to Inventory object

    - moved get_node_counts over from overcloud/deploy.py
    - added more test coverage

    Change-Id: I7774bebb99169aa1da0f07cb2cfc0c1d197af5ca
    Signed-off-by: Dan Radez <dradez@redhat.com>
    (cherry picked from commit ca7b8665dce213c51ae1e15dceede7cc9fba97c1)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 6ddb7d3..f5ff4ff 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 6ddb7d379156ba03c9c4bdcb01679d6727cb4dd6
+Subproject commit f5ff4ff13a1ab3b45454268f1871a2ba5c4cd944