bug: sub domain generator never triggered with share command

[toonvanstrijp]

In the docs there is a section that explains about generating a unique subdomain automatically, but when using the share command it uses a subdomain based on the target for example http://localhost:3000 becomes https://localhost.tunnel.debugged.nl (when no subdomain is given). Because of this the generator is never triggered and used for generating a unique domain as the docs explain.