Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Clone tempest repository in the Docker image"
  - Clone tempest repository in the Docker image

    Rally needs to have a copy of the Tempest repository
    in order to install the verifier. Otherwise, rally will
    clone it automatically anyway.

    This also uplifts the tempest version to 15.0.0 which targets
    Ocata deployments according to [1]

    [1]: https://releases.openstack.org/ocata/

    Change-Id: I30e922a261a4ab1875d48c4754df09426b5f67e4
    Signed-off-by: jose.lausuch <jose.lausuch@ericsson.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 4d66967..e62f0f2 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 4d669670f13e5ab4394a2c9e38073bf7281555ae
+Subproject commit e62f0f289621c843e60f21f69a8e87e7d2778f36