Update surefire-version + configuration in example

git-svn-id: https://svn.apache.org/repos/asf/maven/shared/trunk@1395178 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/site/apt/usage.apt b/src/site/apt/usage.apt
index 7339df3..fbbe970 100644
--- a/src/site/apt/usage.apt
+++ b/src/site/apt/usage.apt
@@ -143,14 +143,11 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
-        <version>2.4.3</version>
+        <version>2.12.4</version> <!-- see surefire-page for available versions -->
         <configuration>
-          <systemProperties>
-            <property>
-              <name>maven.home</name>
-              <value>${maven.home}</value>
-            </property>
-          </systemProperties>
+          <systemPropertyVariables>
+            <maven.home>${maven.home}</maven.home>
+          </systemPropertyVariables>
         </configuration>
       </plugin>
     </plugins>