PEP 681: Fix header links

[JelleZijlstra]

#2481 didn't like the hashes in the URLs

[CAM-Gerlach]

Thanks; I've instead updated #2484 to ensure URL fragments are allowed (e.g. skipping to specific posts, as these are); there's no real harm in doing so and it avoids extra work/frustration from authors having to manually trim them. Therefore, this PR isn't really needed any more, unless you/the author don't want to explicitly jump to the specific messages in the thread.

[JelleZijlstra]

Since it's the top message in the thread, I feel like it's nicer to link to the whole thread.

[CAM-Gerlach]

Yeah, I agree, and upon closer inspection and visiting the links I see the second one actually appears to link to the wrong message (for me in FF on Windows, my browser doesn't actually jump to it when I first visit the page, only when I press enter again on the link with the page loaded—perhaps Hyperkitty has an issue with its JS triggers.

[CAM-Gerlach]

LGTM, thanks @JelleZijlstra