Add Google calendar ID to directive
We hold regular meetings, the timings of which are available on our [public calendar](https://calendar.google.com/calendar/embed?src=c_35r93ec6vtp8smhm7dv5uot0v4%40group.calendar.google.com).
-```{napari-calendar}
+```{calendar}
---
show-filters: true
+calendar-id: c_35r93ec6vtp8smhm7dv5uot0v4%40group.calendar.google.com
---
```
