Update logging.md

Currently `Yii::$app->log` is not the `yii\log\Logger`, but the `yii\log\Dispatcher`. Logger is transient component used indirectly and separately by the dispatcher and helper methods for logging.

docs/guide/logging.md

@@ -32,9 +32,8 @@ There are multiple severity levels and corresponding methods available:
 Log targets
 -----------
 
-When one of the logging methods is called, message is passed to [[yii\log\Logger]] component also accessible as
+When one of the logging methods is called, message is passed to [[yii\log\Logger]] component accessible as
-`Yii::$app->log`. Logger accumulates messages in memory and then when there are enough messages or when current
+`Yii::$app->log->logger` or `Yii::getLogger()`. Logger accumulates messages in memory and then when there are enough messages or when current request finishes, sends them to different log targets, such as file or email.
-request finishes, sends them to different log targets, such as file or email.
 
 You may configure the targets in application configuration, like the following: