Add version for maven-changes-plugin.

git-svn-id: https://svn.apache.org/repos/asf/maven/doxia/doxia/trunk@1311184 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 3367061..6bbaba9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -408,6 +408,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-changes-plugin</artifactId>
+            <version>2.6</version>
             <configuration>
               <columnNames>Type,Key,Summary,Resolution,Assignee</columnNames>
               <maxEntries>1000</maxEntries>