[Docs] Correct example showing the record passed in as param

[x7ryan]

When following this example I discovered I could not call $this->record from that context. After a quick check I discovered the $record must be passed in as a parameter into the closure.

NOTE: There are other examples on this docs page of $this->record that I suspect may also need to be updated but I have not tested that so I am not updating them, unless someone can confirm that is also the case there. I am making this a draft until I can get confirmation on this.

[what-the-diff]

PR Summary

• Update to the Action Method Callback
  The changes in this PR basically improve the functioning of certain methods within our app. Previously, only one parameter was included in our action method 'callback'. But now, a second parameter known as 'Model $record' has been added. This change allows the method to receive more data to work with, thus increasing its effectiveness.

• Record Reference Update
  The amendments have also affected the usage of '$this->record' references as they were changed to a simpler format- just '$record'. This makes the code more straightforward and reduces ambiguity.

• Author Association Change
  The line that associated an author with a given record was modified too. Before it used to be '$this->record->author()->associate($data['authorId'])', but after the change it is now '$record->author()->associate($data['authorId'])'. This streamline ensures that an author can be easily linked with their specific work.

• Removal of 'required' Method on 'authorId' Option
  Lastly, the '.required()' method that was previously called on the 'authorId' option was omitted. We found this wasn't necessary and was actually causing some inefficiencies in our code, as it required certain data to be unnecessarily checked before being processed. This change simply allows for smoother operation as our application no longer needs to check if 'authorId' is present every time.

[danharrin]

Hmm I think you're right and we should move all examples to $record. But $this->record does still work in some places.

[x7ryan]

Yeah I wasn't sure. But I can go ahead and just switch all the examples to $record. Personally that's probably how I'd actually do it instead of having to figure out/remember where $this does and does not work.