LOG4J2-1802: Add changelog entry

Author: jvz

src/changes/changes.xml

@@ -31,6 +31,9 @@
          - "remove" - Removed
     -->
     <release version="3.0.0" date="2018-xx-xx" description="GA Release 3.0.0">
+      <action issue="LOG4J2-1802" dev="mattsicker" type="add">
+        Convert documentation into AsciiDoc format.
+      </action>
       <action issue="LOG4J2-2268" dev="rgoers" type="fix" due-to="Tilman Hausherr">
         Improve plugin error message when elements are missing.
       </action>