add colon at the end of the query

SQL-queries-for-analyze-Matrix-Synapse-PostgreSQL-database-stats.md

@@ -61,7 +61,7 @@ SELECT user_id, SUM(total_events)
    WHERE TO_TIMESTAMP(end_ts/1000) AT TIME ZONE 'UTC' > date_trunc('day', now() - interval '1 month')
    GROUP BY user_id
    ORDER BY SUM(total_events) DESC 
-   LIMIT 20
+   LIMIT 20;
 ```
 
 ## Show top 20 larger tables by storage size