Update git submodules

* Update docs/submodules/appc.git from branch 'master'
  to 639f053e8819d76a254f20f5c0b797ee65965301
  - Volume - Junit Test case added
    
    Volume - Junit Test case added
    
    Issue-ID: APPC-1372
    Change-Id: I44a262819ddc3f0f3319e320ef3bf01ef8ca1e13
    Signed-off-by: Sudarshan Kumar <sudars19@in.ibm.com>
    
1 file changed