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>