make it easier to vote for Assyst

[trueharuu]

What would you like to see added to Assyst?
Either a command (-vote) or more accessible error messages for premium-specific features.

Additional context
Currently, the only way to access the voting links is via -help, which is not easily inferred when the user would want to vote. Aside from this, the current premium error messages tell you that you can vote, but provides no instructions on how to do so.