remove obsolete link to template file (#176)

A link exist on the page: https://maven.apache.org/plugins/maven-site-plugin/index.html

to filetemplate but it was removed in https://github.com/apache/maven-site-plugin/commit/5f81392dadcc6899c17e1c64f6957229514118ff
diff --git a/src/site/apt/index.apt.vm b/src/site/apt/index.apt.vm
index 78e3437..14f6740 100644
--- a/src/site/apt/index.apt.vm
+++ b/src/site/apt/index.apt.vm
@@ -103,8 +103,6 @@
 
 ** Site Template
 
-     * {{{./examples/templatefile.html}Changing the Template File}}
-
      * {{{./examples/creatingskins.html}Creating Skins}}
 
 ** Deploying