Add Data set clarifications

apps/docs/content/guides/database/replication/etl.mdx

@@ -58,7 +58,14 @@ Before setting up replication to BigQuery, you need:
    - **Publication**: Select an existing publication or create a new one
    - **Type**: Select "BigQuery" from the destination types
    - **Project Id**: Enter the GCP project ID
-   - **Project's Dataset Id**: Enter the ID of the BigQuery dataset
+   - **Project's Dataset Id**: Enter the ID of the BigQuery Data set
+
+    <Admonition type="note">
+
+      The BigQuery Data set ID shows the project ID and Data set ID as one string, separated by a ".". The Data set ID is the part after the ".".
+    
+    </Admonition>
+
    - **Service Account Key**: Enter your GCP service account key
 4. Review the [Advanced Settings](#advanced-settings) to change the limits for the replication.