DOC: Fixing links to the contributing page
Not 100% sure on this changes.

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Feel free to close this at anytime.
@MomIsBestFriend the PR fixing the deployment of the dev docs has been merged. There is a problem in statmodels breaking the docs build atm, but the dev docs should be available at  https://pandas.pydata.org/docs/dev/ very soon. If you want to update the links here, that would be great. Thanks! Thanks @MomIsBestFriend 