Update git submodules

* Update docs/submodules/escalator from branch 'master'
  - Merge "The keystoneclient.openstack.common is error path of exception. escalator should use keystoneclient.exception"
  - The keystoneclient.openstack.common is error path of exception.
    escalator should use keystoneclient.exception

    Change-Id: I63a3ad0a9eab9b47bf536cebf4c142b7df22d3c2
    Signed-off-by: Kong Wei<kong.wei2@zte.com.cn>

diff --git a/docs/submodules/escalator b/docs/submodules/escalator
index 872bef9..6a4f961 160000 (submodule)
--- a/docs/submodules/escalator
+++ b/docs/submodules/escalator
@@ -1 +1 @@
-Subproject commit 872bef90d91089812110e31927354a5e9e27af4c
+Subproject commit 6a4f961b61dfdb41d77dcec262bcda64f44689dd