fix a bug that bad namespace spell in agent.config (#6829)

apm-sniffer/config/agent.config

@@ -108,7 +108,7 @@ plugin.mount=${SW_MOUNT_FOLDERS:plugins,activations}
 # Kafka producer configuration
 # plugin.kafka.bootstrap_servers=${SW_KAFKA_BOOTSTRAP_SERVERS:localhost:9092}
 # if you want to set namespace. please make sure the OAP server has set it in Kafka fetcher module
-# plugin.kafka.namspacce=${SW_KAFKA_NAMESPACE:""}
+# plugin.kafka.namespace=${SW_KAFKA_NAMESPACE:""}
 
 # Match spring bean with regex expression for classname
 # plugin.springannotation.classname_match_regex=${SW_SPRINGANNOTATION_CLASSNAME_MATCH_REGEX:}