RecurrenceRule

A recurrence rule describes a repeating pattern of times. Recurrences rules in SavvyCal are modeled after the conventions of [iCalendar](https://en.wikipedia.org/wiki/ICalendar) recurrence rules (RRULE), but are a subset of the full specification.

{  "byday": [    "mo",    "we",    "fr"  ],  "freq": "weekly"}