Docker agent command fixs

[amx-piap]

The title is self explanary. To launch the agent, it would be better to delete it after. Also the different parameters are not working for foxy. I guess a working solution would be:

docker run -it --net=host --rm microros/micro-ros-agent:foxy udp4 --port 9999 # for udp4

docker run -it --net=host --rm microros/micro-ros-agent:foxy udp6 --port 9999 # for udp6

Thank you. Best

[pablogs9]

I think that we should refactor this readme or mark it as deprecated.