refactor: add comment about mongoose default timestamp fields

Author: Bentroen

server/src/song/entity/song.entity.ts

@@ -9,6 +9,8 @@ import type {
 } from '@shared/validation/song/dto/types';
 import { HydratedDocument, Schema as MongooseSchema, Types } from 'mongoose';
 
+import { User } from '@server/user/entity/user.entity';
+
 @Schema({
   timestamps: true,
   versionKey: false,
@@ -24,13 +26,13 @@ export class Song {
   publicId: string;
 
   @Prop({ type: MongooseSchema.Types.Date, required: true, default: Date.now })
-  createdAt: Date;
+  createdAt: Date; // Added automatically by Mongoose: https://mongoosejs.com/docs/timestamps.html
 
   @Prop({ type: MongooseSchema.Types.Date, required: true, default: Date.now })
-  updatedAt: Date;
+  updatedAt: Date; // Added automatically by Mongoose: https://mongoosejs.com/docs/timestamps.html
 
   @Prop({ type: MongooseSchema.Types.ObjectId, required: true, ref: 'User' })
-  uploader: Types.ObjectId;
+  uploader: Types.ObjectId | User; // Populated with the uploader's user document
 
   @Prop({ type: String, required: true })
   thumbnailUrl: string;