Update resolvers.mdx

Enhance the doc for CRUDResolver

documentation/docs/graphql/resolvers.mdx

@@ -1306,6 +1306,8 @@ Lets create a new query endpoint that only returns completed `TodoItems`.
 
 First create a file named `types.ts`. And add the following.
 
+**NOTE** IN the case of `CRUDResolver` the DTO (`TodoItemDTO`) must be placed in file on its own and cannot be placed together with the module definition.
+
 ```ts title="types.ts"
 import { ConnectionType, QueryArgsType } from '@nestjs-query/query-graphql';
 import { ArgsType } from '@nestjs/graphql';
@@ -1399,3 +1401,23 @@ Finally we call the `queryMany` method from the `CRUDResolver` with the new filt
 return this.queryMany({ ...query, ...{ filter } });
 ```
 
+The last step is to add the resolver to the module.
+
+```ts title="todo-items.module.ts"
+import { Module } from '@nestjs/common';
+import { NestjsQueryTypeOrmModule } from '@nestjs-query/query-typeorm';
+import { TodoItemEntity } from './todo-item.entity';
+import { TodoItemsService } from './todo-items.service';
+import { TodoItemsController } from './todo-items.controller';
+import { TodoItemsResolver } from './todo-items.resolver';
+
+@Module({
+  providers: [TodoItemsService, TodoItemsResolver],
+  imports: [
+    NestjsQueryTypeOrmModule.forFeature([TodoItemEntity]),
+  ],
+  exports: [TodoItemsService],
+  controllers: [TodoItemsController],
+})
+export class TodoItemsModule {}
+```