message: Added documentation about new model
diff: @@ -31,6 +31,7 @@ export class UnitController {
  * "description": "...",
  * "markdown": "# What is Lorem Ipsum?\n**Lorem Ipsum** is simply dummy text of the printing and typesetting industry.",
  * "_course": "5a037e6b60f72236d8e7c83b",
  + * "unitCreator": "5a037e6b60f72236d8e7c834",
  * "type": "free-text",
  * "__v": 0
  * }
  @@ -67,6 +68,7 @@ export class UnitController {
  * "markdown": "# What is Lorem Ipsum?\n**Lorem Ipsum** is simply dummy text of the printing and typesetting industry.",
  * "_course": "5a037e6b60f72236d8e7c83b",
  * "type": "free-text",
  + * "unitCreator": "5a037e6b60f72236d8e7c834",
  * "__v": 0
  * }
  *
  @@ -82,6 +84,7 @@ export class UnitController {
  addUnit(@Body() data: any, @CurrentUser() currentUser: IUser) {
  // discard invalid requests
  this.checkPostParam(data);
  + //Set current user as creator, old unit's dont have a creator
  data.model.unitCreator = currentUser._id.toString();
  return Unit.create(data.model)
  