docs: Add iceberg output connector to Cloud docs (#514)

* docs: Add iceberg output connector to Cloud docs

Include the iceberg output connector from rp-connect-docs using the
standard single-source pattern. Iceberg was introduced in Redpanda
Connect 4.80.0 and writes streaming data to Apache Iceberg tables via
REST catalog.

- Create output page including from rp-connect-docs page with
  tag=single-source (matching the pattern used by all other connectors)
- Add iceberg to nav.adoc alphabetically in outputs section
- Add entry to whats-new-cloud.adoc under March 2026

Depends on redpanda-data/rp-connect-docs#378.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* update local playbook for preview

* revert playbook

* test build

* incorporate doc review feedback

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: micheleRP

modules/ROOT/nav.adoc

@@ -193,6 +193,7 @@
 **** xref:develop:connect/components/outputs/gcp_bigquery.adoc[]
 **** xref:develop:connect/components/outputs/gcp_cloud_storage.adoc[]
 **** xref:develop:connect/components/outputs/gcp_pubsub.adoc[]
+**** xref:develop:connect/components/outputs/iceberg.adoc[]
 **** xref:develop:connect/components/outputs/http_client.adoc[]
 **** xref:develop:connect/components/outputs/inproc.adoc[]
 **** xref:develop:connect/components/outputs/kafka.adoc[]

modules/develop/pages/connect/components/outputs/iceberg.adoc

@@ -0,0 +1,3 @@
+= iceberg
+:page-aliases: components:outputs/iceberg.adoc
+include::redpanda-connect:components:outputs/iceberg.adoc[tag=single-source]

modules/get-started/pages/whats-new-cloud.adoc

@@ -10,6 +10,9 @@ This page lists new features added to Redpanda Cloud.
 
 === Redpanda Connect updates
 
+* Outputs:
+** xref:develop:connect/components/outputs/iceberg.adoc[iceberg]: Write data to Apache Iceberg tables using the REST catalog.
+
 * Inputs:
 ** xref:develop:connect/components/inputs/aws_dynamodb_cdc.adoc[aws_dynamodb_cdc] (beta): Consume item-level changes from DynamoDB Streams with automatic checkpointing and shard management.