Document verify command usage

[ddugovic]

Have you checked the features section before making a request?

• Yes
• No

Are you sure if we add this feature, users will be happy about it?

• Yes
• No
• Maybe

Is this related to a problem, if so, please describe:
No, it's not.

Now tell me what's your suggestion
I guessed that !verify is a command, but I don't know its usage. I thought the purpose of this bot was to add a role.

Examples (screenshots etc.) and additional context

[eggsy]

You can use help <cmd_name> to see the description of each command. You can also take a look at the code and find the description field. The verify command is meant to remove all the existing roles from a user and force starts a new verification process. Removing every role is required as users should not have access to any channel (at least the ones that are hidden until users verify themselves).