Add release note for 1.1.0 in NEWS.md (#5763)
Add release note for 1.1.0 in NEWS.md (#5763)

* Add release note for 1.1.0 in NEWS.md

* Address reviewer's feedback
dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost