Upgrade documentation including install process

[mcuadros]

Too add a example systemd service file.

[vonovak]

yes, would be nice to have better docs

[kurdin]

+1

[rosscdh]

+1 great looking project nfi how to run it. Standard go seems not to work

 go run dockershipd.go                                                                                                                      (master✱)
# github.com/mcuadros/dockership/http
../../../go_work/src/github.com/mcuadros/dockership/http/server.go:99: undefined: Asset
../../../go_work/src/github.com/mcuadros/dockership/http/server.go:107: undefined: Asset
../../../go_work/src/github.com/mcuadros/dockership/http/server.go:115: undefined: Asset
../../../go_work/src/github.com/mcuadros/dockership/http/server.go:123: undefined: Asset
../../../go_work/src/github.com/mcuadros/dockership/http/server.go:131: undefined: Asse