Update git submodules

* Update docs/submodules/apex from branch 'stable/euphrates'
  - Merge "Fix Neutron data_plane_status extension path" into stable/euphrates
  - Fix Neutron data_plane_status extension path

    This way is easier to patch than patching file
    neutron.egg-info/entry_points.txt, plus this feature is backported
    to Ocata so it's temporary and only applicable for Euphrates.

    From Pike we can move it back to 'data_plane_status' as it was before.

    Change-Id: I1c2ebc55e782463793e7a8e463cc17fdf899457a
    Signed-off-by: Carlos Goncalves <mail@cgoncalves.pt>
    (cherry picked from commit 3ad85e5753dd4b0bf621f5d92f45725d18070e54)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 991531f..9697719 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 991531fc2b0f71705962c7cf1fe467e03bab4aa7
+Subproject commit 96977197df5ad0be9fea91ce17d332288fdbbf09