Update documentation of IImsConfig interface.

import com.android.ims.ImsConfigListener;

/**

 * Provides APIs to get/set the IMS service capability/parameters.

 * The parameters can be configured by operator and/or user.

 * We define 4 storage locations for the IMS config items:

 * 1) Default config:For factory out device or device after factory data reset,

 * the default config is used to build the initial state of the master config value.

 * 2) Provisioned value: as the parameters provisioned by operator need to be preserved

 * across FDR(factory data reset)/BOTA(over the air software upgrade), the operator

 * provisioned items should be stored in memory location preserved across FDR/BOTA.

 * 3) Master value: as the provisioned value can override the user setting,

 * and the master config are used by IMS stack. They should be stored in the

 * storage based on IMS vendor implementations.

 * 4) User setting: For items can be changed by both user/operator, the user

 * setting should take effect in some cases. So the user setting should be stored in

 * database like setting.db.

 * Provides APIs to get/set the IMS service feature/capability/parameters.

 * The config items include:

 * 1) Items provisioned by the operator.

 * 2) Items configured by user. Mainly service feature class.

 *

 * Priority consideration if both operator/user can config the same item:

 * 1)  For feature config items, the master value is obtained from the provisioned value

 * masks with the user setting. Specifically the provisioned values overrides

 * the user setting if feature is provisioned off. Otherwise, user setting takes

 * effect.

 * 2) For non-feature config item: to be implemented based on cases.

 * Special cases considered as below:

 * 1) Factory out device, the master configuration is built from default config.

 * 2) For Factory data reset/SW upgrade device, the master config is built by

 * taking provisioned value overriding default config.

 * {@hide}

 */

interface IImsConfig {