fix: README update on docker usage (#43)

* use docker to setup a local dev chain.

* install docker link

* update command

* Update README.md

Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>

* more commands to start or check a node.

* purge chain in docker

* update README

Co-authored-by: Kaichao Sun <kaichaosuna@gmail.com>
Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>