Update git submodules

* Update docs/submodules/orchestra from branch 'stable/euphrates'
  - Added release notes for 5.1.0

    Change-Id: I318e2e21d83c214b21e8ca4ab25b79458c55945f
    Signed-off-by: Giuseppe Carella <cargius@gmail.com>

diff --git a/docs/submodules/orchestra b/docs/submodules/orchestra
index f739870..1f0d8ed 160000 (submodule)
--- a/docs/submodules/orchestra
+++ b/docs/submodules/orchestra
@@ -1 +1 @@
-Subproject commit f7398707955225379babe44d3e00e74b25b15475
+Subproject commit 1f0d8ed7261f1b202476680b2e3fc2d41b399cc9