Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - Add flavor metadata for volume related tests

    These tests are very sensitive to the state of instance which might be
    active in terms of nova, but in fact still trying to get an ip address in
    case of dpdk scenarios.

    Change-Id: I739044c2edd360535ce1d3531549263163cfea19
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/snaps b/docs/submodules/snaps
index dc76020..88c9496 160000 (submodule)
--- a/docs/submodules/snaps
+++ b/docs/submodules/snaps
@@ -1 +1 @@
-Subproject commit dc76020bee7085a3e2e9d1bd94e4ad7904d3b77d
+Subproject commit 88c9496ee5d40adbb324c0d449ed1659e661d700