Updated nav.adoc for new migrate files (#1192)

also added the LTS updates to the nav

docs/modules/ROOT/nav.adoc

@@ -33,7 +33,9 @@
 * xref:getting-started:install-enterprise.adoc[Install {enterprise-product-name}]
 ** xref:deploy:enterprise-licenses.adoc[Managing Enterprise license keys]
 * xref:getting-started:install-hazelcast.adoc[Install {open-source-product-name}]
-// * xref:placeholder.adoc[Upgrade to Enterprise from OSS/Community]
+* xref:migrate:lts.adoc[]
+* xref:migrate:community-to-enterprise.adoc[]
+** xref:migrate:rolling-restart.adoc[]
 * xref:migrate:data-migration-tool.adoc[]
 * Upgrades
 ** xref:migrate:upgrading-from-jet.adoc[]