Document all tags and named sub-components

Closes #9

calendar.go

@@ -10,6 +10,16 @@ var _ tomo.Object = new(Calendar)
 
 // Calendar is an object that can display a date and allow the user to change
 // it. It can display one month at a time.
+// 
+// Sub-components:
+//   - CalendarGrid organizes the days into a grid.
+//   - CalendarWeekdayHeader appears at the top of each grid column, and shows
+//     the day of the week that column represents.
+//   - CalendarDay appears within the grid for each day of the current month.
+//
+// CalendarDay tags:
+//   - [weekend] The day is a weekend.
+//   - [weekday] The day is a weekday.
 type Calendar struct {
 	box tomo.ContainerBox