Rework model docstrings for progressive disclosure of complexity

[mattdangerw]

We need to simplify our model docstring so they are more easily understandable, and we can start by porting the changes in #843 to all other models.

Let's do this one model at a time, to keep things granular.

Checklist:

• Make sure to update any "custom vocabulary" examples to match the model actual vocabulary type and special token requirements (varies per model).
• Test out all docstring snippets!
• Make sure to follow our code style guidelines re indentation etc.

[mattdangerw]

Also, we are getting a lot of contributor interest right now! Let's all try to..

• Use this issue to communicate.
• Only work on a single model at a time. E.g. wait till you have a PR ready for one model before starting on the next.
• Be patient with each other as we all self organize here :)

Thanks!

[shivance]

I can take this up for Roberta. Thanks.

[ADITYADAS1999]

Thanks for this issues & guideline, I want to work with f_net model.

[Cyber-Machine]

@mattdangerw I'd like to work with Distil_bert model. Thanks

[soma2000-lang]

@mattdangerw I am working on albert

[TheAthleticCoder]

I shall take this up for deberta_v3 then

[abuelnasr0]

I am working with GPT2

[Warlord-K]

@mattdangerw I'd like to take up opt.

[abuelnasr0]

I will take XLMRoberta instead of GPT-2 for now as it is not exported to keras_nlp library to be used in colab to test docsting snippets. I will continue my work with GPT-2 after installing dependencies in my local machine soon.

[soma2000-lang]

I am taking up t5

[susnato]

I am taking this up for Whisper.

[shivance]

@mattdangerw & @chenmoneygithub RoBERTa is still pending.
@abuelnasr0 is a new contributor interested in contributing to KerasNLP. As the issue is mostly good first issue, it can be good start for him.
Abu you can start working on this issue for RoBERTa, good luck !

[mattdangerw]

Yeah, sorry this issue might keep getting marked as close due to thing like "Partially fixes #867" in the PR description. Will keep reopening for now.

[mattdangerw]

Also thanks everyone for the work on this issue!