Update git submodules

* Update docs/submodules/container4nfv from branch 'master'
  - Merge "add Arm64 specific HPA documentation"
  - add Arm64 specific HPA documentation

    Heterogeneous computing is an important feature for a typical
    NFV scenario (Edge computing, Access networking).

    This document list specific hardware features for Arm64.
    Later, I will add more features in it.

    Change-Id: I5db29dd3842eb80dd707c762d7847c08e5b74252
    Signed-off-by: Bin Lu <bin.lu@arm.com>

diff --git a/docs/submodules/container4nfv b/docs/submodules/container4nfv
index 8d92e07..6535bcc 160000 (submodule)
--- a/docs/submodules/container4nfv
+++ b/docs/submodules/container4nfv
@@ -1 +1 @@
-Subproject commit 8d92e07e2b6d56dfc182f4da4d97899301f30410
+Subproject commit 6535bcca66f3dcee06a454f5b37e499701cc59a7