Update git submodules

* Update docs/submodules/apex from branch 'stable/euphrates'
  - Use stable/17.10 branch for VPP

    also add retry and timeout for VPP interface check in os-net-config

    apex-os-net-config: Idaf03d78d2ce657ac484c1285a795d98760d0112

    Change-Id: I3dca43d263923e2ae7ff84781d3f7aa64fad6b5d
    Signed-off-by: Feng Pan <fpan@redhat.com>
    (cherry picked from commit 89932c44597ae86e8460939896f978862005596f)

diff --git a/docs/submodules/apex b/docs/submodules/apex
index 8c9675c..205eb09 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit 8c9675c16e4350aa855c2d2c847fb18eed3a72ec
+Subproject commit 205eb09eccd5661dda9ab627c99aab6175783e9b