Update git submodules

* Update docs/submodules/apex from branch 'stable/danube'
  - Merge "Updating docs for Danube" into stable/danube
  - Updating docs for Danube

    Change-Id: I7eb2d7bb62d61ca1ab7177332bb27329da85ad48
    Signed-off-by: Dan Radez <dradez@redhat.com>
    (cherry picked from commit a684f6b753749c355aee06412bd0f22779357089)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 9b6f46e..8300dc9 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 9b6f46e48cc123be0ea731b7a92d3c80f29a6d17
+Subproject commit 8300dc9ab70a051d627c1ed67486a38ee74f213a