`rofl deploy` add a hint for the `top-up` command

[matevz]

Lots of hackathoners didn’t know for the rofl machine top-up command. The instance expired after 1h and they needed to redeploy a new machine.

Write down an expiration date after a successful deployment below with a hint that you can extend renting machine with the machine top-up command.

[rube-de]

Adding the top-up command in the docs would help too.
Makes it also easier to just link it when someone has an expired app in discord or hackathon