Update git submodules

* Update docs/submodules/promise from branch 'stable/euphrates'
  - Added support for Keystone v3

    JIRA: PROMISE-80

    Change-Id: I5e904da373e2d5309456a6ce7ec56e724a62791f
    Signed-off-by: Bertrand Souville <souville@docomolab-euro.com>
    (cherry picked from commit bd9acd199e55efc097443d8c99027cf0030b5e78)

diff --git a/docs/submodules/promise b/docs/submodules/promise
index 5698eda..4b9d723 160000 (submodule)
--- a/docs/submodules/promise
+++ b/docs/submodules/promise
@@ -1 +1 @@
-Subproject commit 5698eda65d99786a9668bd00e49b5a158be90c35
+Subproject commit 4b9d723b6e6e368536d43c8f511e6eeb35c7f27a