Update README.md with release 1.6 information
Update README.md with release 1.6 information

frakc/DraggablePanel,dfodor/DraggablePanel,pedrovgs/DraggablePanel,ppamorim/DraggablePanel,hoangsondev/DraggablePanel,murat8505/DraggablePanel,hmit/DraggablePanel,qiwx2012/DraggablePanel,SPBTV/DraggablePanel,Fiddl3/DraggablePanel,Thornith/DraggablePanel,FreeDao/DraggablePanel