!notify docs

!notify: stores a message to be displayed to another person at a later date.

General syntax: !notify <username> <message>
	Stores the message to be displayed the next time <username> speaks.
Special syntaxes:
	!notify @join <username> <message>
		stores the message to be displayed to <username> when they join the chat.
	!notify @in <time> <message>
		the message will be displayed after the specified time passes.
		Time is written in the form hh:mm or hh:mm:ss. Leading zeroes may be omitted.
		examples:
			20 hours 33 minutes → !notify @in 20:33 Hi.
			18 minutes → !notify @in 0:18 Hi.
			2 hours 1 minute → !notify @in 2:01 Hi.
			2 hours 1 minute can also be written "!notify @in 2:1 Hi."

	!notify @in <number> <time unit> <message>
		the message will be displayed after the specified time passes.
		<time unit> can be seconds, minutes, hours, days, weeks, months, or years.
		e.g. !notify @in 2 minutes Hi.

	!notify @date <date> <message>
		the message will be displayed on the date specified.
		The date must be written in the format specified by RFC3339.
		examples:
			May 30, 2014 at 16:22:43 UTC → 2014-05-30T16:22:43
			February 29, 2012 at 5:01:22 UTC → 2012-02-29T05:01:22