version 15 is not released yet

git-svn-id: https://svn.apache.org/repos/asf/maven/pom/trunk@1580204 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/asf/src/site-docs/apt/index.apt b/asf/src/site-docs/apt/index.apt
index f77191c..0b24ce0 100644
--- a/asf/src/site-docs/apt/index.apt
+++ b/asf/src/site-docs/apt/index.apt
@@ -117,7 +117,7 @@
 *--------------+------------+
 || <<Version>> || <<Release Date>> ||
 *--------------+------------+
-| {{{http://svn.apache.org/viewvc/maven/pom/tags/apache-15/pom.xml?view=markup}15}} ({{{http://svn.apache.org/viewvc/maven/pom/tags/apache-15/pom.xml?r1=HEAD&r2=1575044&diff_format=h}diff}}) | 2014-03-06 |
+| {{{http://svn.apache.org/viewvc/maven/pom/tags/apache-15/pom.xml?view=markup}15}} ({{{http://svn.apache.org/viewvc/maven/pom/tags/apache-15/pom.xml?r1=HEAD&r2=1575044&diff_format=h}diff}}) |  |
 *--------------+------------+
 | {{{http://svn.apache.org/viewvc/maven/pom/tags/apache-14/pom.xml?view=markup}14}} ({{{http://svn.apache.org/viewvc/maven/pom/tags/apache-14/pom.xml?r1=HEAD&r2=1434717&diff_format=h}diff}}) | 2014-03-06 |
 *--------------+------------+