Update git submodules

* Update docs/submodules/policy/engine.git from branch 'master'
  to 563918147277421156c372d8ee0096e42ed17e99
  - Upgrade elasticsearch to 6.4.1
    
    Recommendation is to upgrade to clear security vulnerability
    as described in the JIRA.
    
    Issue-ID: POLICY-1538
    Change-Id: If6a55ffcf4babb7547e52a7971061e9c9a197c43
    Signed-off-by: Pamela Dragosh <pdragosh@research.att.com>
    
1 file changed