DOC-1437 Recommend oauth2

Author: kbatuigas

modules/manage/partials/iceberg/use-iceberg-catalogs.adoc

@@ -60,6 +60,11 @@ To connect to a REST catalog, set the following cluster configuration properties
 * config_ref:iceberg_catalog_type,true,properties/cluster-properties[`iceberg_catalog_type`]: `rest`
 * config_ref:iceberg_rest_catalog_endpoint,true,properties/cluster-properties[`iceberg_rest_catalog_endpoint`]: The endpoint URL for your Iceberg catalog, which you either manage directly, or is managed by an external catalog service.
 * config_ref:iceberg_rest_catalog_authentication_mode,true,properties/cluster-properties[`iceberg_rest_catalog_authentication_mode`]: The authentication mode to use for the REST catalog. Choose from `oauth2`, `bearer`, or `none` (default).
+ifdef::env-cloud[]
++
+Redpanda recommends using `oauth2`.
+
+endif::[]
 ** For `oauth2`, also configure the following properties:
 +
 --
@@ -111,6 +116,11 @@ Run the following `rpk` command:
 ----
 rpk security secret create --name <secret-name> --value <secret-value> --scopes redpanda_cluster
 ----
+
+Replace the placeholders with your own values:
+
+- `<secret-name>`: The name of the secret you want to add. The secret name is also its ID. Use only the following characters: `^[A-Z][A-Z0-9_]*$`.
+- `<secret-value>`: The value of the secret.
 --
 
 Cloud API::

modules/reference/pages/properties/cluster-properties.adoc

@@ -2068,6 +2068,10 @@ endif::[]
 
 The authentication mode for client requests made to the Iceberg catalog. Choose from: `none`, `bearer`, and `oauth2`. In `bearer` mode, the token specified in `iceberg_rest_catalog_token` is used unconditionally, and no attempts are made to refresh the token. In `oauth2` mode, the credentials specified in `iceberg_rest_catalog_client_id` and `iceberg_rest_catalog_client_secret` are used to obtain a bearer token from the URI defined by `iceberg_rest_catalog_oauth2_server_uri.`.
 
+ifdef::env-cloud[]
+Redpanda recommends using `oauth2`.
+endif::[]
+
 *Requires restart:* Yes
 
 *Visibility:* `user`