Update git submodules

* Update docs/submodules/sdc.git from branch 'master'
  to 31c64b3443fb1a76d1cfc7afc0db1e51f1ffda79
  - HEAT to TOSCA VM Consolidation
    
    Change-Id: I00c9cf90d7486af33955acae7dfe653e14ceebdc
    Issue-ID: SDC-2997
    Signed-off-by: Ben David, Elad (eb7504) <eb7504@intl.att.com>
    
1 file changed