Update order of guides in nav.adoc

Author: jgrandja

docs/modules/ROOT/nav.adoc

@@ -5,9 +5,9 @@
 * xref:core-model-components.adoc[]
 * xref:protocol-endpoints.adoc[]
 * xref:how-to.adoc[]
-** xref:guides/how-to-ext-grant-type.adoc[]
-** xref:guides/how-to-jpa.adoc[]
 ** xref:guides/how-to-pkce.adoc[]
 ** xref:guides/how-to-social-login.adoc[]
+** xref:guides/how-to-ext-grant-type.adoc[]
 ** xref:guides/how-to-userinfo.adoc[]
+** xref:guides/how-to-jpa.adoc[]
 ** xref:guides/how-to-custom-claims-authorities.adoc[]