[DOCS] Add descriptive docstring to MinNewTokensLength (#25196)
* Add descriptive docstring to MinNewTokensLength
It addresses https://github.com/huggingface/transformers/issues/24783
* Refine the differences between `min_length` and `min_new_tokens`
* Remove extra line
* Remove extra arguments in generate
* Add a missing space
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
* Run the linter
* Add clarification comments
---------
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>