add rpk pages to nav & fix new index pages

Author: micheleRP

modules/ROOT/nav.adoc

@@ -610,6 +610,15 @@
 ***** xref:reference:rpk/rpk-security/rpk-security-user-delete.adoc[]
 ***** xref:reference:rpk/rpk-security/rpk-security-user-update.adoc[]
 ***** xref:reference:rpk/rpk-security/rpk-security-user-list.adoc[]
+*** xref:reference:rpk/rpk-shadow/rpk-shadow.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-config-generate.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-create.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-delete.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-describe.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-failover.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-list.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-status.adoc[]
+**** xref:reference:rpk/rpk-shadow/rpk-shadow-update.adoc[]
 *** xref:reference:rpk/rpk-topic/rpk-topic.adoc[]
 **** xref:reference:rpk/rpk-topic/rpk-topic-add-partitions.adoc[]
 **** xref:reference:rpk/rpk-topic/rpk-topic-alter-config.adoc[]

modules/manage/pages/disaster-recovery/index.adoc

@@ -1,4 +1,5 @@
 = Disaster Recovery
 :description: Learn about disaster recovery options for Redpanda Cloud.
+:page-layout: index
 
-include::ROOT:manage:disaster-recovery/index.adoc[tag=single-source]
+Shadowing complements Redpanda's existing availability and recovery capabilities. High availability actively protects your day-to-day operations, handling reads and writes seamlessly during node or availability zone failures within a region. Shadowing is your safety net for catastrophic regional disasters. Shadowing delivers near real-time, cross-region replication for mission-critical applications that require rapid failover with minimal data loss.

modules/manage/pages/disaster-recovery/shadowing/index.adoc

@@ -1,4 +1,3 @@
 = Shadowing
 :description: Learn about shadowing for disaster recovery in Redpanda Cloud.
-
-include::ROOT:manage:disaster-recovery/shadowing/index.adoc[tag=single-source]
+:page-layout: index