message: Update doc from peer review
diff: @@ -1424,7 +1424,7 @@ void mongo_db_plugin::set_program_options(options_description& cli, options_desc
  ("mongodb-store-action-traces", bpo::value<bool>()->default_value(true),
  "Enables storing action traces in mongodb.")
  ("mongodb-filter-on", bpo::value<vector<string>>()->composing(),
  - "Mongodb: Track actions which match receiver:action:actor. Actor may be blank to include all. Action and Actor both blank allows all from Receiver. Receiver may not be blank.")
  + "Mongodb: Track actions which match receiver:action:actor. Action and/or Actor may be blank to include all. Action and Actor both blank allows all from Receiver. Receiver may not be blank.")
  ("mongodb-filter-out", bpo::value<vector<string>>()->composing(),
  "Mongodb: Do not track actions which match receiver:action:actor. Action and Actor both blank excludes all from Receiver. Actor blank excludes all from receiver:action. Receiver may not be blank.")
  ;
  