Update git submodules

* Update docs/submodules/appc.git from branch 'master'
  to 391f3dbd2d9c65a8d9a6a512b1274c2ad170f144
  - Change to snapshot parent version
    
    Change to appc parent version 2.6.3-SNAPSHOT
    
    Change-Id: I51e4485098a271ff80de64ea6c20a81df94c7d8f
    Signed-off-by: Patrick Brady <patrick.brady@att.com>
    Issue-ID: APPC-1686
    
1 file changed