Update git submodules

Update git submodules

* Update docs/submodules/kvmfornfv from branch 'stable/danube'
  - This patch is used to update the documents of D-release.

    Change-Id: I059843a8967ec339b8faf87dcbc6a76ec15d25d4
    Co-Authored by:Srinivas <srinivas.atmakuri@tcs.com>
    Co-Authored by:RajithaY<rajithax.yerrumsetty@intel.com>
    Co-Authored by:Gundarapu Kalyan Reddy <reddyx.gundarapu@intel.com>
    Co-Authored by:Navya Bathula <navyax.bathula@intel.com>
    Signed-off-by: Shravani <shravani.p@tcs.com>
    (cherry picked from commit d4b19c2012c72015c7554ad0b0f098b9dae8aa7c)