Update git submodules

* Update docs/submodules/promise from branch 'master'
  - Proposal to remove deprecated shim-layer implementation

    Change-Id: I8ef21e0c349c0b3b62f3598bab4d90edfa801e7b
    Signed-off-by: Bertrand Souville <souville@docomolab-euro.com>

diff --git a/docs/submodules/promise b/docs/submodules/promise
index c23e113..335b844 160000 (submodule)
--- a/docs/submodules/promise
+++ b/docs/submodules/promise
@@ -1 +1 @@
-Subproject commit c23e1136d5e036476a7720ce841d73c19bcc99d7
+Subproject commit 335b8446a9cb142b82a6b5cd1c2231d8185416c9