incorrect docs description.

Document: [Using commands directly](https://github.com/yiisoft/yii2-redis/blob/master/docs/guide/usage-commands.md)

```
//Incorrect
$result = $redis->hmset(['test_collection', 'key1', 'val1', 'key2', 'val2']);

//correct 
$result = $redis->hmset('test_collection', 'key1', 'val1', 'key2', 'val2');
```
