Remove link to tycho extras documentation

Bug: 559558
Change-Id: I802ced37ba6488a1b13a1dd2eefa6dc445511cb6
Signed-off-by: Michael Keppler <Michael.Keppler@gmx.de>
diff --git a/documentation.php b/documentation.php
index 258c2e8..d77f4f6 100644
--- a/documentation.php
+++ b/documentation.php
@@ -18,19 +18,14 @@
 <p>The documentation of the Tycho project is maintained in the <a href="https://wiki.eclipse.org/Category:Tycho">Eclipse wiki</a>.</p>
 
 <p>
-For an introduction to Tycho , we recommend following the <a href="https://www.eclipsecon.org/2013/node/1277.html">EclipseCon Tycho Tutorial</a>.
+For an introduction to Tycho, we recommend following the <a href="https://www.eclipsecon.org/2013/node/1277.html">EclipseCon Tycho Tutorial</a>.
 </p>
 
 <p>In order to set up Tycho in a Maven build, follow the instructions and examples on the pages
 <a href="https://wiki.eclipse.org/Tycho/Reference_Card">Tycho Reference Card</a> and <a href="https://wiki.eclipse.org/Tycho/Packaging_Types">Tycho Packaging Types</a>.
 </p>
 
-<p>For detailed reference documentation, refer to
-<ul>
-  <li><a href="sitedocs/index.html">Maven plugin documentation for Tycho</a></li>
-  <li><a href="sitedocs-extras/index.html">Maven plugin documentation for Tycho Extras</a></li>
-</ul>
-
+<p>For detailed reference documentation, refer to the <a href="sitedocs/index.html">Maven plugin documentation for Tycho</a>.
 </p>
 
 <p>Other sources of information: