Add a note command

[schanzb]

I think it would be really good to have a feature where you can note a specific user and it will show up whenever they open a ticket in the same place logs show up. For example, you could note if a user has a history of abusing the bot or frequently asks stupid questions, allowing mods to warn someone before they get blocked from using the bot.

[SuperSajuuk]

This is an okay idea, but a !note command exists [for a different purpose] so there would be collision. What you're asking for is probably better suited for a moderation bot imo as you can just use a mod bot for logging warnings in a similar manner.

[bycop]

I've created a pull request with this feature, if you want to comment it !

[DarkView]

Added with #589