Enhance SQL on-demand guide with master database tip

Added a tip about selecting the master database in Synapse Studio.

Author: whhender

articles/synapse-analytics/get-started-analyze-sql-on-demand.md

@@ -51,6 +51,9 @@ However, as you continue data exploration, you might want to create some utility
 - Database users with the permissions to access some data sources or database objects.
 - Utility views, procedures, and functions that you can use in the queries.
 
+> [!TIP]
+> > In Synapse Studio, when you open a new SQL script, you can select master from the database dropdown menu in the top toolbar. This is the default system database that appears for serverless SQL pools.
+
 1. Use the `master` database to create a separate database for custom database objects. Custom database objects can't be created in the `master` database.
 
    ```sql