Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Disables ODL clustering for FDIO+ODL scenarios

    ODL clustering has issues with VPP mounting, so we are disabling
    clustering for now and should have the bug in ODL fixed by Danube 2.0.

    Change-Id: I19b9c9167596105a3197de8c5a537bed1280f241
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 7d6129c..5108498 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 7d6129c6ce008c9ea9cc73c5e2a0f0062050d48a
+Subproject commit 5108498adb2870581cc5a4bb99db693a05ff9c3b