Added relations import to readme.

Author: Chriztiaan

packages/drizzle-driver/README.md

@@ -13,6 +13,7 @@ Set up the PowerSync Database and wrap it with Drizzle.
 ```js
 import { wrapPowerSyncWithDrizzle } from '@powersync/drizzle-driver';
 import { PowerSyncDatabase } from '@powersync/web';
+import { relations } from 'drizzle-orm';
 import { index, integer, sqliteTable, text } from 'drizzle-orm/sqlite-core';
 import { appSchema } from './schema';