Update docs on setting global settings

docs/advanced-usage/8-setting-global-configuration.md

@@ -0,0 +1,19 @@
+---
+title: Setting global configurations
+weight: 8
+---
+
+At this moment, there is no way of setting global configuration for producers/consumers, but you can use laravel `macro` functionality
+to achieve that. Here's an example:
+
+
+```php
+// In a service provider:
+
+\Junges\Kafka\Facades\Kafka::macro('myProducer', function () {
+    return $this->publishOn('my-awesome-topic')
+        ->withConfigOption('key', 'value');
+});
+```
+
+Now, you can call `\Junges\Kafka\Facades\Kafka::myProducer()`, which will always apply the configs you defined in your service provider.