Add a command to add categories as needed.

[Kitty-Therapist]

Currently there is a limitation of how many categories that you can have and they are a bit hard-coded at the moment.

I want to improve on that, and do something like !category add <name> which would go into the server's JSON config file.

When the category is created, the submission message can be said when users submit in that category "Thank you for submitting in the <new category name, will pull from JSON config of the category name associated to the channel sent>!" for example.