Clarify the advertise-httpAddress step

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: stephanos

docs/production-deployment/self-hosted-guide/temporal-nexus.mdx

@@ -108,9 +108,10 @@ target an external URL (`--target-url`), which is experimental and not covered h
    [Multi-Cluster Replication](/self-hosted-guide/multi-cluster-replication) for
    connecting Clusters and creating replicated Namespaces.
 
-2. **Advertise a frontend HTTP address on every Cluster.** Extend the `httpPort`
-   and `clusterInformation.<cluster>.httpAddress` from [Enable Nexus](#enable-nexus)
-   to **every** Cluster, each with its own address.
+2. **Advertise a frontend HTTP address on every Cluster.** [Enable Nexus](#enable-nexus)
+   sets `frontend.rpc.httpPort` and `clusterInformation.<cluster>.httpAddress` for
+   one Cluster. Set both on **every** Cluster, each with its own address, so the
+   other Clusters can reach it to deliver callbacks.
 
 3. **Register Endpoints on every Cluster.** The
    [Nexus Endpoint registry](/nexus/registry) isn't replicated across Clusters.