Introduce categories in command handlers.

[WiseDevHelper]

Is your feature request related to a problem? Please describe.

As we keep adding commands, the commands folder seems untidy with the large number of files it contains.
I feel that it would be better if the commands were sorted out neatly.

Describe the solution you'd like

If there was a follow up on the main guide about this topic, people would easily implement this in their code instead of searching the internet for a long time, confused with the large number of options presented and unsure about what the best solution is.

Additional notes

This will be useful both to new learners, and old coders who are looking for an alternative.

[meister03]

This seems to be a good Suggestion. But starters on Discord.js should have a good start. Adding more code, would confuse them more. You could make it as additional feature. You have to weigh it up, when you start without categories. The problem is it will be then a habbit

[iShibi]

#573 introduces the above-requested feature. The PR does need some changes, which will be done by tomorrow.

[iShibi]

Added in #573 🎉