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 5f81392

Author: ebarboni

src/site/apt/index.apt.vm

@@ -103,8 +103,6 @@ ${project.name}
 
 ** Site Template
 
-     * {{{./examples/templatefile.html}Changing the Template File}}
-
      * {{{./examples/creatingskins.html}Creating Skins}}
 
 ** Deploying