Doc: fix reference to PEP 528

[mitya57]

Trivial change in the whatsnew documentation.

[the-knights-who-say-ni]

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[mitya57]

My b.p.o account did not have my GitHub username, added it now.

[csabella]

LGTM.

@1st1, would you be able to review as you made the original change? Thanks!

[bedevere-bot]

@1st1: Please replace # with GH- in the commit message next time. Thanks!

[miss-islington]

Thanks @mitya57 for the PR, and @1st1 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.6, 3.7.
🐍🍒⛏🤖

[1st1]

Thanks!

[bedevere-bot]

GH-7256 is a backport of this pull request to the 3.7 branch.

[bedevere-bot]

GH-7257 is a backport of this pull request to the 3.6 branch.