Update git submodules

* Update docs/submodules/aaf/certservice.git from branch 'master'
  to 71986212d4088b3cc5c41c2ed96ec352ea899fe5
  - Add Certification Client documentation
    
    Issue-ID: AAF-1091
    Signed-off-by: Tomasz Wrobel <tomasz.wrobel@nokia.com>
    Change-Id: I8eb762063767f8532845e7f66b1d7398468ab650
    
1 file changed