Improve flag type display

[AllanOricil]

I think this feature I developed would improve dx

The word <value> is really not useful. cli devs have to describe the flag type in its description, and users are required to read the description just to learn/remember what type of value they have to pass to that particular flag.

Besides that, I also believe this improvement makes the help output look more close to what developers are used to when dealing with variables and its types when writting code.