Change Kafka server host property reference (#109)

Updated Kafka server host configuration to use spring.kafka.bootstrap-servers.

Author: timonback

docs/quickstart.mdx

@@ -37,7 +37,7 @@ springwolf.docket.info.title=${spring.application.name}
 springwolf.docket.info.version=1.0.0
 
 springwolf.docket.servers.kafka-server.protocol=kafka
-springwolf.docket.servers.kafka-server.host=${kafka.bootstrap.servers:localhost:29092}
+springwolf.docket.servers.kafka-server.host=${spring.kafka.bootstrap-servers:localhost:29092}
 ```
 
 *Make sure to change the value of `springwolf.docket.base-package` to the package containing your listeners, so that Springwolf will automatically pick them up.*