Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - Merge "Changed heat_utils#get_stack_by_name to get_stack."
  - Changed heat_utils#get_stack_by_name to get_stack.

    Added stack_settings parameter to allow for more robust
    queries based on the known settings as required.

    JIRA: SNAPS-158

    Change-Id: I538826f822307365b1afe997b71280b9ea500eab
    Signed-off-by: spisarski <s.pisarski@cablelabs.com>

diff --git a/docs/submodules/snaps b/docs/submodules/snaps
index 13e1764..84d9026 160000 (submodule)
--- a/docs/submodules/snaps
+++ b/docs/submodules/snaps
@@ -1 +1 @@
-Subproject commit 13e17646bccbcafbac13b144e24eee14125d33e3
+Subproject commit 84d902632f1dd77f891c49cfb1d58af5ae051d1a