Update git submodules

* Update docs/submodules/armband from branch 'master'
  - u/fuel: Bump & rebase for glance signature and vpp

    Change-Id: I20256794b1ef31410527329e0e4a9a730d93ce03
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>

diff --git a/docs/submodules/armband b/docs/submodules/armband
index b9af498..d6ff3a1 160000 (submodule)
--- a/docs/submodules/armband
+++ b/docs/submodules/armband
@@ -1 +1 @@
-Subproject commit b9af498cb689f2018442461834c6f4013158500a
+Subproject commit d6ff3a19ef707db95e38589598c5fcbc194d6032