docs: Add new plan for backend structure

backend/src/users/library/library.module.ts

@@ -0,0 +1,4 @@
+import { Module } from '@nestjs/common';
+
+@Module({})
+export class LibraryModule {}

backend/src/users/play-state/play-state.module.ts

@@ -0,0 +1,4 @@
+import { Module } from '@nestjs/common';
+
+@Module({})
+export class PlayStateModule {}

backend/src/users/users.module.ts

@@ -3,9 +3,11 @@ import { UsersService } from './users.service';
 import { userProviders } from './user.providers';
 import { UsersController } from './users.controller';
 import { DatabaseModule } from '../database/database.module';
+import { LibraryModule } from './library/library.module';
+import { PlayStateModule } from './play-state/play-state.module';
 
 @Module({
-  imports: [DatabaseModule],
+  imports: [DatabaseModule, LibraryModule, PlayStateModule],
   providers: [...userProviders, UsersService],
   controllers: [UsersController],
   exports: [UsersService],