Update Calendar main comment

import android.util.Log;

/**

 * The Calendar provider contains all calendar events.

 * <p>

 * The contract between the calendar provider and applications. Contains

 * definitions for the supported URIs and data columns.

 * </p>

 * <h3>Overview</h3>

 * <p>

 * CalendarContract defines the data model of calendar and event related

 * information. This data is stored in a number of tables:

 * </p>

 * <ul>

 * <li>The {@link Calendars} table holds the calendar specific information. Each

 * row in this table contains the details for a single calendar, such as the

 * name, color, sync info, etc.</li>

 * <li>The {@link Events} table holds the event specific information. Each row

 * in this table has the info for a single event. It contains information such

 * as event title, location, start time, end time, etc. The event can occur

 * one-time or can recur multiple times. Attendees, reminders, and extended

 * properties are stored on separate tables and reference the {@link Events#_ID}

 * to link them with the event.</li>

 * <li>The {@link Instances} table holds the start and end time for occurrences

 * of an event. Each row in this table represents a single occurrence. For

 * one-time events there will be a 1:1 mapping of instances to events. For

 * recurring events, multiple rows will automatically be generated which

 * correspond to multiple occurrences of that event.</li>

 * <li>The {@link Attendees} table holds the event attendee or guest

 * information. Each row represents a single guest of an event. It specifies the

 * type of guest they are and their attendance response for the event.</li>

 * <li>The {@link Reminders} table holds the alert/notification data. Each row

 * represents a single alert for an event. An event can have multiple reminders.

 * The number of reminders per event is specified in

 * {@link Calendars#MAX_REMINDERS} which is set by the Sync Adapter that owns

 * the given calendar. Reminders are specified in minutes before the event and

 * have a type.</li>

 * <li>The {@link ExtendedProperties} table hold opaque data fields used by the

 * sync adapter. The provider takes no action with items in this table except to

 * delete them when their related events are deleted.</li>

 * </ul>

 * <p>

 * Other tables include:

 * </p>

 * <ul>

 * <li>

 * {@link SyncState}, which contains free-form data maintained by the sync

 * adapters</li>

 * </ul>

 * 

 * @hide

 */