Update kafka-config.md
Fix name of spring-kafka property to pass SASL_JAAS config
@@ -8,7 +8,7 @@ export KAFKA_BOOTSTRAP_SERVER=broker:29092
export KAFKA_SCHEMAREGISTRY_URL=http://schema-registry:8081
export SPRING_KAFKA_PROPERTIES_SASL_KERBEROS_SERVICE_NAME=kafka
export SPRING_KAFKA_PROPERTIES_SECURITY_PROTOCOL=SASL_PLAINTEXT
-export SPRING_KAFKA_SASL_JAAS_CONFIG=com.sun.security.auth.module.Krb5LoginModule required principal='principal@REALM' useKeyTab=true storeKey=true keyTab='/keytab';
+export SPRING_KAFKA_PROPERTIES_SASL_JAAS_CONFIG=com.sun.security.auth.module.Krb5LoginModule required principal='principal@REALM' useKeyTab=true storeKey=true keyTab='/keytab';
```
These properties can be specified via `application.properties` or `application.yml` files, or as command line switches, or as environment variables. See Spring's [Externalized Configuration](https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-external-config) to see how this works.
