fixed example in rest help

I'm not sure if there must be a leading "/"  as in `pinoccio rest get /v/1/1/command --command led.report`

in the api docs [https://docs.pinocc.io/api.html#cli] there's an example without leading slash:
`pinoccio rest get v1/troops`

Anyway, the previous example provided with `pinoccio help rest` was wrong and always return "undefined"