Update git submodules

* Update docs/submodules/apex from branch 'master'
  - 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>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 0fc3c21..ca7b866 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 0fc3c2190ad304052d0ec210c94ab3f09e95b71d
+Subproject commit ca7b8665dce213c51ae1e15dceede7cc9fba97c1