Port Add Maven example for Tomcat 8

Port Add Maven example for Tomcat 8 from markdown to asciidoc.
(originally from commit 15372cb)

Author: Phillip Webb

spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -477,7 +477,25 @@ of ways. Or the nuclear option is to add your own `JettyEmbeddedServletContainer
 [[howto-use-tomcat-8]]
 === Use Tomcat 8
 Tomcat 8 works with Spring Boot, but the default is to use Tomcat 7 (so we can support
-Java 1.6 out of the box). You should only need to change the classpath to use Tomcat 8
+Java 1.6 out of the box). You should only need to change the classpath to use
+Tomcat 8 for it to work. For example, using the starter poms in Maven:
+
+[source,xml,indent=0,subs="verbatim,quotes,attributes"]
+----
+	<properties>
+		<tomcat.version>8.0.3</tomcat.version>
+	</properties>
+	<dependencies>
+		...
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+		...
+	</dependencies>
+----
+
+change the classpath to use Tomcat 8
 for it to work. The {github-code}/spring-boot-samples/spring-boot-sample-websocket/pom.xml[websocket sample]
 shows you how to do that in Maven.