chore(kafka): add quickstart and update beta status (#1437)

Author: scaleway-bot

scaleway-async/scaleway_async/kafka/v1alpha1/api.py

@@ -55,7 +55,7 @@
 
 class KafkaV1Alpha1API(API):
     """
-    This API allows you to manage your Clusters for Apache Kafka®. This product is currently in Private Beta.
+    This API allows you to manage your Clusters for Apache Kafka®. This product is currently in Public Beta.
     """
 
     async def list_node_types(

scaleway/scaleway/kafka/v1alpha1/api.py

@@ -55,7 +55,7 @@
 
 class KafkaV1Alpha1API(API):
     """
-    This API allows you to manage your Clusters for Apache Kafka®. This product is currently in Private Beta.
+    This API allows you to manage your Clusters for Apache Kafka®. This product is currently in Public Beta.
     """
 
     def list_node_types(