updated maven-site-plugin to 3.6

git-svn-id: https://svn.apache.org/repos/asf/maven/pom/trunk@1770164 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/asf/pom.xml b/asf/pom.xml
index 0538add..8cdd448 100644
--- a/asf/pom.xml
+++ b/asf/pom.xml
@@ -241,7 +241,7 @@
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-site-plugin</artifactId>
-          <version>3.5.1</version>
+          <version>3.6</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>