[docs] duplicate sentences in document_question_answering.mdx

[jungnerd]

Description

There are duplicate sentences in document_question_answering.mdx from line number 40 to 45.

Document / Language

document_question_answering.mdx / en

Suggestion

should be either:

candidate 1	candidate 2
(...), to predict the positions of the start and end tokens of the answer. (...)	(...), in order to predict which token is at the start of the answer and which token is at the end of the answer. (...)

Please let me know which of the two candidates you would prefer.

[sgugger]

I'd prefer candidate 1 personally. Thanks for reporting and looking forward to your PR with a fix!

[jungnerd]

Thanks for your feedback and I agree that candidate 1 is better. I opened PR #23735.