Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Merge "Change install directory for collectd-ceilometer from /opt to /opt/stack."
  - Change install directory for collectd-ceilometer from /opt to /opt/stack.

    Change-Id: I9dd9d69a7efa7c037b776a416bf54df8d2c7b712
    Signed-off-by: jhinman1 <john.hinman@intel.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 0bf4a8d..cf46710 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 0bf4a8d12a5eb2be0c2767370347109309c2a06e
+Subproject commit cf46710061125a4959c8997ee38ca8959c5d2634