@1st1 and/or @asvetlov, would you mind giving this a final look-over before we add these whatsnews entries? Since it's a backwards incompatible change to asyncio affecting multiple versions (for anyone passing reuse_address=True to loop.create_datagram_endpoint()), I want to make sure we communicate it as well as possible.

Is the current iteration adequate or should it be more specific? My goal was to avoid adding too many details in the whatsnew entry and explain most of it in the documentation.