docs: add example output after creating postgres role (#17451)

Added example output showing what the roles table should look like after
creating the postgres role

Co-authored-by: Tom Larson <tomlarson@Toms-MacBook-Pro.local>

packages/twenty-docs/developers/contribute/capabilities/local-setup.mdx

@@ -159,6 +159,12 @@ You should run all commands in the following steps from the root of the project.
       CREATE ROLE postgres WITH SUPERUSER LOGIN;
     ```
     This creates a superuser role named `postgres` with login access.
+      ```bash
+      Role name | Attributes  | Member of
+      -----------+-------------+-----------
+      postgres  | Superuser   | {}
+      john      | Superuser   | {}
+    ```
 
     **Option 2:** If you have docker installed:
     ```bash