Require at least Maven 3.0 for build

* JDK 9 EA now includes http://openjdk.java.net/jeps/280
  So that execution of build with "javac -target 1.9"
  requires at least version 2.4 of maven-shade-plugin
  (https://issues.apache.org/jira/browse/MSHADE-174),
  which in his turn requires at least Maven 3.0.

* Maven 2.x has reached its end of life
  and is no longer supported by Apache Maven Project Team
  (http://maven.apache.org/maven-2.x-eol.html).
diff --git a/org.jacoco.doc/docroot/doc/changes.html b/org.jacoco.doc/docroot/doc/changes.html
index b0f3df7..5bf8f95 100644
--- a/org.jacoco.doc/docroot/doc/changes.html
+++ b/org.jacoco.doc/docroot/doc/changes.html
@@ -20,6 +20,12 @@
 
 <h2>Snapshot Build @qualified.bundle.version@ (@build.date@)</h2>
 
+<h3>Non-functional Changes</h3>
+<ul>
+  <li>Require at least Maven 3.0 for build of JaCoCo.</li>
+</ul>
+
+
 <h2>Release 0.7.6 (2016/02/18)</h2>
 
 <h3>New Features</h3>