add template for release notes

Author: romani

net.sf.eclipsecs.doc/src/main/templates/release_notes.html

@@ -0,0 +1,16 @@
+<div>
+    <h3>Changes</h3>
+    <ul>
+        ###CONTENT###
+    </ul>
+    
+    <p>
+        Please read the
+        <a target="_blank" href="http://checkstyle.sourceforge.net/releasenotes.html">
+            Checkstyle release notes
+        </a>
+        for details on recent and potentially breaking changes in Checkstyle.
+        Checkstyle configuration files potentially
+        need to be adapted to this version.
+    </p>
+</div>