Update git submodules

* Update docs/submodules/armband from branch 'stable/euphrates'
  - u/fuel: Bump & rebase for cinder retry

    While at it, refresh Armband GPG public key embedded in maas config.

    Change-Id: Id69677102ae8fea7a962578bae44e930afea8200
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/armband b/docs/submodules/armband
index 1c1cd04..d1de887 160000 (submodule)
--- a/docs/submodules/armband
+++ b/docs/submodules/armband
@@ -1 +1 @@
-Subproject commit 1c1cd04959057f18cf8dc4f0331def50f0066442
+Subproject commit d1de8877810d0ab0a6e0381e370f5eaa3b07e52d