Update git submodules

* Update docs/submodules/apex from branch 'stable/danube'
  - Fixing zrpcd is not starting

    JIRA: APEX-437
    JIRA: APEX-448

    Signed-off-by: Nikolas Hermanns <nikolas.hermanns@ericsson.com>
    Change-Id: I91c1b3bef83c808166072e00c751d8fac3565b5f
    (cherry picked from commit d81cd2087be5edf5d2c0d98ad71a63360ae8511f)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index c67baa8..168e9e9 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit c67baa84baf6e5d5d1b07c0b9468e2435d50a970
+Subproject commit 168e9e92a39d03b5455938dfa7269017602e99e8