Update git submodules

Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - Merge "Adding SDNVPN test cases to the Optional Test areas of the CVP."
  - Adding SDNVPN test cases to the Optional Test areas of the CVP.

    Included the tests for SDNVPN in the docetail scope document
    Performed spell checking of the committed test area document and included
    the section around test suite structure.  This patch should be reviewed
    and approved by the SDNVPN team prior to being merged.

    Change-Id: Ia2f9a1bddb02b9191da1239a73f121dce6687af1
    Co-Authored-By: Georg Kunz <georg.kunz@ericsson.com>
    Co-Authored-By: ChristopherPrice <christopher.price@ericsson.com>
    Signed-off-by: ChristopherPrice <christopher.price@ericsson.com>
    Signed-off-by: Georg Kunz <georg.kunz@ericsson.com>