Update git submodules

* Update docs/submodules/sfc from branch 'master'
  - Merge "Move the yamllint check to tox"
  - Move the yamllint check to tox

    Until now we were executing the yamllint check through shell
    commands contained to a builder in the releng repo [0].
    This patch moves that check to the tox framework.

    Additional changes should be done to the sfc jobs in the
    releng repo.

    [0]: https://github.com/opnfv/releng/blob/master/jjb/sfc/sfc-project-jobs.yaml#L73

    Change-Id: Ie42113087a8c1494593d5510cdf367abe99a7f5b
    Signed-off-by: Dimitrios Markou <mardim@intracom-telecom.com>

diff --git a/docs/submodules/sfc b/docs/submodules/sfc
index 3e0ba96..60e21cb 160000 (submodule)
--- a/docs/submodules/sfc
+++ b/docs/submodules/sfc
@@ -1 +1 @@
-Subproject commit 3e0ba9638fd98d43f3b2f632351c2edb556d03af
+Subproject commit 60e21cbdbe94e32060369304b0502fe5b03af2c4