Added synchronize warning in database docs

Author: WillSquire

content/recipes/sql-typeorm.md

@@ -39,6 +39,8 @@ export const databaseProviders = [
 ];
 ```
 
+> warning **Warning** Setting `synchronize: true` shouldn't be used in production - otherwise you can lose production data.
+
 > warning **Hint** Following best practices, we declared the custom provider in the separated file which has a `*.providers.ts` suffix.
 
 Then, we need to export these providers to make them **accessible** for the rest of the application.

content/techniques/sql.md

@@ -40,6 +40,8 @@ import { TypeOrmModule } from '@nestjs/typeorm';
 export class AppModule {}
 ```
 
+> warning **Warning** Setting `synchronize: true` shouldn't be used in production - otherwise you can lose production data.
+
 The `forRoot()` method supports all the configuration properties exposed by the `createConnection()` function from the [TypeORM](https://typeorm.io/#/connection-options) package. In addition, there are several extra configuration properties described below.
 
 <table>