Further WebFlux and Messaging Reactor Sleuth improvements (#1699)

* Improving performance and adding docs

benchmarks/pom.xml

@@ -28,7 +28,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>2.4.0-M1</version>
+		<version>2.4.0-SNAPSHOT</version>
 		<relativePath/> <!-- lookup parent from repository -->
 	</parent>
 
@@ -147,6 +147,11 @@
 			<groupId>org.apache.httpcomponents</groupId>
 			<artifactId>httpclient</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.awaitility</groupId>
+			<artifactId>awaitility</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<build>