Revert "Updated docs for Kafka binder configuration"

This reverts commit 47bb27db12.

docs/src/main/asciidoc/spring-cloud-sleuth.adoc

@@ -351,30 +351,6 @@ NOTE: the sample consumer application above explicitly excludes
 but this is optional (you might actually want to trace requests into
 the consumer app).
 
-=== Spring Cloud Stream Kafka binder configuration
-
-In order to integrate header propagation with Spring Cloud Stream Kafka as a binder you have to provide in your
-configuration file the following headers:
-
-[source,yaml]
-----
-spring:
-  cloud:
-    stream:
-      kafka:
-        binder:
-           headers:
-             - X-B3-TraceId
-             - X-B3-SpanId
-             - X-B3-Sampled
-             - X-B3-ParentSpanId
-             - X-Span-Name
-             - X-Process-Id
-----
-
-TIP: If you have a custom `SpanExtractor<Message<?>` where you pass custom headers you need to provide those too in the
-configuration file.
-
 == Metrics
 
 Currently Spring Cloud Sleuth registers very simple metrics related to spans.