Provide links to v3 html when we know we have it in announcements

`resolution_fixed` `type_defect`   |    by brian.e.carpenter@gmail.com

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See
https://mailarchive.ietf.org/arch/msg/i-d-announce/YhsUdVRNI9N55n68FP1KCqQrLsk/

Both that, and the new version announcement would have been better if there was a link available for the generated v3 html.

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_Issue migrated from trac:3067 at 2022-03-04 07:59:10 +0000_