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.
Widget 'yii\authclient\widgets\Choice' renamed to 'yii\authclient\widgets\AuthChoice'
Microsoft Live OAuth2 client added.
Tabs replaced by spaces at AuthChoice asset files.
Merge pull request #2996 from hijarian/patch-1

Update logging.md
minor doc fix. [skip ci]
First round of edits

Pretty awesome feature!