Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "Add parameter of `DEPLOY_SCENARIO` for doctor"
  - Add parameter of `DEPLOY_SCENARIO` for doctor

    Need to get the os_cacert file according to the scenario for MCP installer.
    You can see here: https://github.com/opnfv/releng/blob/master/utils/fetch_os_creds.sh#L116

    Change-Id: I9216f2c810a93a25406a33e2f9c542c64f30e27e
    Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a87d08f..cf9cc97 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a87d08f26c1a8f2b99e03dc3b0654fb3e9796382
+Subproject commit cf9cc976185da259eca1b3e8722b75a9855e8f8c