Update git submodules

* Update docs/submodules/appc.git from branch 'master'
  to 6cbb73628f72e90fb8219cc7120326ef55a91653
  - Change parent to release version 2.7.1
    
    Change-Id: I87d105f7c59c0e65bc12ef5e92f708696081f7b1
    Signed-off-by: Patrick Brady <patrick.brady@att.com>
    Issue-ID: APPC-1816
    
1 file changed