[Doctest] Add configuration_big_bird.py
Hi!

Updating configuration_big_bird.py

Based on issue https://github.com/huggingface/transformers/issues/19487

Tests passed
![image](https://user-images.githubusercontent.com/49692939/195433142-d6c12962-1d36-4868-a754-e20766230233.png)

_The documentation is not available anymore as the PR was closed or merged._<|||||>Hey, there seems to be a problem with this line
![image](https://user-images.githubusercontent.com/49692939/195444333-07c19198-5011-4423-9578-fa85ec7ce294.png)

Check_code_quality is returning this error:
![image](https://user-images.githubusercontent.com/49692939/195444639-3244e864-ebc6-4bc2-987a-980db6667ac1.png)

When I tried to keep it below 119 in length and move some of the text to the next line I got another error
![image](https://user-images.githubusercontent.com/49692939/195445536-98f17a58-484b-4608-8d04-c82ab72f06d6.png)

Thus I can not add this 'with random weights' text and I am wondering how to solve this problem.
