Update git submodules

Update git submodules

* Update docs/submodules/doctor 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

    This patch is part of our documentation effor to Move away from
    submodules
    https://docs.opnfv.org/en/latest/how-to-use-docs/local-build-transition.html

    Your project is now required to have a docs/index.rst so if you are
    missing this file please create it.

    Change-Id: I32a91a4194e4afe98f4c964052e99419b22330ba
    Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>