Add JDBC to nav

Issue gh-2827

Author: marcusdacoregio

spring-session-docs/modules/ROOT/nav.adoc

@@ -25,6 +25,7 @@
 *** xref:guides/xml-jdbc.adoc[JDBC]
 * xref:configurations.adoc[Configurations]
 ** xref:configuration/redis.adoc[Redis]
+** xref:configuration/jdbc.adoc[JDBC]
 ** xref:configuration/common.adoc[Common Configurations]
 * xref:http-session.adoc[HttpSession Integration]
 * xref:web-socket.adoc[WebSocket Integration]