Update git submodules

* Update docs/submodules/snaps from branch 'master'
  - Merge "Local Documentation Builds"
  - Local Documentation Builds

        This adds configuration for performing local documentation builds
        with the following simple command:

        tox -e docs

    added index.rst so that docs build succsesfully

    Change-Id: Iab747c90f7f4b7866270c5850b2792e194b5378a
    Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>

diff --git a/docs/submodules/snaps b/docs/submodules/snaps
index 630875f..12bdf41 160000 (submodule)
--- a/docs/submodules/snaps
+++ b/docs/submodules/snaps
@@ -1 +1 @@
-Subproject commit 630875f0ac88239f0b9207312793f4d39a5e36bd
+Subproject commit 12bdf4134e0d627b96540f514d479600f73a8545