Servlet Authentication no a link in nav

docs/modules/ROOT/nav.adoc

@@ -15,7 +15,7 @@
 * xref:servlet/index.adoc[Servlet Applications]
 ** xref:servlet/getting-started.adoc[Getting Started]
 ** xref:servlet/architecture.adoc[The Big Picture]
-** Authentication
+** xref:servlet/authentication/index.adoc[Authentication]
 *** xref:servlet/authentication/architecture.adoc[Authentication Architecture]
 *** xref:servlet/authentication/passwords/index.adoc[Username/Password]
 **** Reading Username/Password