Suggestion: Allow to decide which roles can config the bot

[winston-yallow]

Current Behaviour
The bot requires the "manage server" permission to configure it.

Suggested Behaviour
You can set which role can configure the bot. For this a command like /config set manager-role:<role name> would be useful.

[VelvetToroyashi]

👋🏽 Just wanted to pop here to say that Discord is slowly rolling out a V2 for slash command permissions, and you'll be able to configure this natively through the client; Ben will still have to lift the restriction in the code, but that's pretty trivial.