add instructions around official dcos packages
add instructions around official dcos packages

BuoyantIO/linkerd-examples,linkerd/linkerd-examples,BuoyantIO/linkerd-examples,jasonjckn/linkerd-examples,linkerd/linkerd-examples,ewilde/linkerd-examples-1,BuoyantIO/linkerd-examples,linkerd/linkerd-examples,jasonjckn/linkerd-examples,ewilde/linkerd-examples-1,jasonjckn/linkerd-examples,BuoyantIO/linkerd-examples,jasonjckn/linkerd-examples,ewilde/linkerd-examples-1,ewilde/linkerd-examples-1,jasonjckn/linkerd-examples,linkerd/linkerd-examples