Updated readme

Author: Rentacookie

demos/nodejs-mssql/README.md

@@ -26,3 +26,17 @@ The frontend can be accessed at `http://localhost:3036` in a browser.
 
 See [MSSQL Configuration](../../services/mssql/mssql.yaml) for the SQL server configuration 
 The SQL server is initialized with the [init](../../services/mssql/init.sql) script. 
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+The initialization script (`init.sql`) performs the following setup steps:
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+1. **Database Creation**: Creates the application database
+2. **CDC Setup**: Enables Change Data Capture at the database level
+3. **User Creation**: Creates a SQL Server login and database user with appropriate permissions
+4. **Create PowerSync Checkpoints table**: Creates the required `_powersync_checkpoints` table.
+5. **Self Host Demo Tables**: Creates the demo tables (`lists` and `todos`)
+6. **Enable Table CDC**: Enables CDC tracking on the demo tables
+7. **Permissions**: Grants `db_datareader` and `cdc_reader` roles to the application user
+8. **Sample Data**: Inserts initial test data into the `lists` table
+
+All operations are idempotent, so they can safely be re-run without errors.
+