Update git submodules

* Update docs/submodules/policy/engine.git from branch 'master'
  to 1c6e9a8e8b4fa260e882348b54f3e748fb19ad4c
  - Remove nexus staging plugin
    
    Unused
    
    Issue-ID: POLICY-1737
    Change-Id: I3e287ecbca9707d04f566295ebc5d0d430980d81
    Signed-off-by: pdragosh <pdragosh@research.att.com>
    
1 file changed