Update git submodules

* Update docs/submodules/apex from branch 'stable/danube'
  - Updating Linux kernel licensing info to GPL v2 with a new link

    Change-Id: I463a26299c9b76123b3c6d3374cd2ed391fcdc99
    Signed-off-by: Ray Paik <rpaik@linuxfoundation.org>
    (cherry picked from commit 6aac03ac5f3985b0f03220451bf71028e63dbe07)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index fc13f72..8d69ed9 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit fc13f72801b95cf5707554088c8c81c557cda2be
+Subproject commit 8d69ed9b013375ecdab2fb6ddaba3ee0c71079af