README: Add list of features.
README: Add list of features.

Signed-off-by: Andrea Luzzardi <442ffe3ffbfd024afcf0b7f8b108d05bca3aae43@gmail.com>

alyyousuf7/swarmkit,cheyang/swarmkit,Noyan759/swarmkit,vasil-yordanov/swarmkit,Noyan759/swarmkit,jlhawn/swarmkit,alyyousuf7/swarmkit,aaronlehmann/swarmkit,elifa/swarmkit,yp-engineering/swarmkit,dperny/swarmkit-1,AliyunContainerService/swarmkit,diogomonica/swarmkit,cheyang/swarmkit,aaronlehmann/swarmkit,allencloud/swarmkit,diogomonica/swarmkit,yp-engineering/swarmkit,vasil-yordanov/swarmkit,sungwonh/swarmkit,docker/swarmkit,jlhawn/swarmkit,fate-grand-order/swarmkit,allencloud/swarmkit,yongtang/swarmkit,yongtang/swarmkit,sungwonh/swarmkit,runshenzhu/swarmkit,runshenzhu/swarmkit,deljuven/swarmkit,deljuven/swarmkit,elifa/swarmkit,RenaudWasTaken/swarmkit,AliyunContainerService/swarmkit,docker/swarmkit,RenaudWasTaken/swarmkit,cezarsa/swarmkit,fate-grand-order/swarmkit,cezarsa/swarmkit,dperny/swarmkit-1