fix(mongo): use correct semantics for an array field

Author: unrevised6419

content/techniques/mongo.md

@@ -86,7 +86,7 @@ In case there are multiple owners, your property configuration should look as fo
 
 ```typescript
 @Prop({ type: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Owner' }] })
-owner: Owner[];
+owners: Owner[];
 ```
 
 Finally, the **raw** schema definition can also be passed to the decorator. This is useful when, for example, a property represents a nested object which is not defined as a class. For this, use the `raw()` function from the `@nestjs/mongoose` package, as follows: