Doc overrides for Kafka 2.7.0

Author: garyrussell

src/reference/asciidoc/appendix.adoc

@@ -7,6 +7,8 @@ This is especially true when using the embedded Kafka broker in `spring-kafka-te
 
 IMPORTANT: Backwards compatibility is not supported for all Boot versions; Spring for Apache Kafka 2.6 has been tested with Spring Boot 2.4 and 2.3.
 
+You can also use this technique to override the kafka libraries to 2.7.0 with Spring for Apache Kafka 2.6.x.
+
 **maven**
 
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