Update git submodules

* Update docs/submodules/msb/apigateway.git from branch 'master'
  to 6d8a9b3bc718e868f7edcdbeb0485722a37943cb
  - Merge "release 1.2.6"
  - release 1.2.6
    
    Issue-ID: MSB-463
    
    Signed-off-by: Huabing Zhao <zhao.huabing@zte.com.cn>
    Change-Id: I3b04bc929a773495d2129fa8c75d74c521495441
    
1 file changed