Add back homu-ignore markers around the PR template

[steffahn]

Besides reinstantiating the homu-ignore markers from #126501, this PR also adds better clarification how the homu-ignore markers actually work; I've then also moved that section further down as it seems less important than the other parts of the PR template message. (We shouldn't forget that this is a general PR template message, not a LLM-policy-specific message.)

The disclosure markers appear to have been accidentally removed together with the checkboxes in #160785.

In the future, if support for ignoring HTML comments in places such as markdown code blocks was added, the new description about how <!-- homu-ignore:end -->/<!-- homu-ignore:start --> can be used could be further simplified¹, but I'd like to address the immediate issues first before considering any more involved improvements (there already exist [currently 6 8] new PRs now that contain the whole template comment without homu-ignore markers).

Footnotes

1. actually it may always stay non-ideal given that HTML comments don't nest 🫠 ↩

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[steffahn]

I've fixed the (8) affected open PRs manually for now.¹ Will do that a second time once this is merged.

(I've also fixed a handful of older cases based on the previous version of the template, where authors had accidentally removed the homu-ignore:end together with the HTML comment, while keeping the boxes and homu-ignore:start.)

Footnotes

1. Finding relevant PRs with gh api '/repos/rust-lang/rust/pulls?page=1' | jq 'map({ number, body })' + using the search functionality of my terminal ↩

[jieyouxu]

Thanks
@bors r+ rollup

View changes since this review

[rust-bors]

📌 Commit 0bcefa1 has been approved by jieyouxu

It is now in the queue for this repository.

[jieyouxu]

@bors p=1 note="can be rolled up, just noisy in git commit history"

[steffahn]

I've manually fixed 2 more PRs' descriptions now so it's all handled, good to have gotten this merged so quickly ^^ - thanks @jieyouxu

(Another 5 new PRs were already opened since, at the time of this writing, that benefitted from this so far, as those now do contain the comments properly guarded again.)

[steffahn]

As for unfixed "broken" cases that got through: 6 cases¹ of LLM checkboxes made it into git history, 4 of which contain unmatched homu-ignore:start markers (where the author had accidentally removed the homu-ignore:end together with the informative comment from the template, when the template still had the checkboxes).

No case of the Please read our [LLM policy] … comment has made it into commit messages.

Footnotes

1. You can find those e.g. with git log --grep "\] I did not use an LLM" on an up to date checkout of the rust repo. ↩