docs: fix broken changelog link

[MartinMa]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Documentation content changes

What is the current behavior?

• Link is broken

Issue Number: N/A

What is the new behavior?

• Link is working

Does this PR introduce a breaking change?

• No

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