Update howto.adoc

Author: PatrikSteuer

docs/src/main/asciidoc/howto.adoc

@@ -162,8 +162,11 @@ Add the Sleuth starter, exclude Brave, add OTel and Zipkin to the classpath.
         <groupId>org.springframework.cloud</groupId>
         <artifactId>spring-cloud-sleuth-zipkin</artifactId>
     </dependency>
-
-
+    <dependency>
+      <groupId>io.opentelemetry</groupId>
+      <artifactId>opentelemetry-exporter-zipkin</artifactId>
+    </dependency>
+    
 		<!-- You 'll need those to add OTel support -->
 		<repositories>
 			<repository>
@@ -575,4 +578,4 @@ Below you can find the examples:
 @Component
 include::{autoconfig_path}/src/test/java/org/springframework/cloud/sleuth/autoconfig/otel/OtelPropagationConfigurationTests.java[tags=custom_propagator,indent=0]
 ----
-====
+====