docs: update AGENTS.md bot-review section to current CodeRabbit reality (backport #2188)

[mergify]

What

The ### Bot review workflow section of AGENTS.md documented a
manual-invocation flow that no longer matches how this repository
actually works, and the ## CI list was missing the AI Validation
workflow. This PR corrects both.

.github/copilot-instructions.md is a symlink to AGENTS.md, so it
picks up the same correction automatically — no separate edit.

Why

The section told contributors to comment @copilot review on a draft,
iterate until Copilot went silent, then flip to ready and comment
@coderabbitai review. It also asserted that "auto-reviews are disabled
on this repo". Following those instructions today produces the wrong
behavior: the manual CodeRabbit trigger is redundant with the automatic
review, and the Copilot invocation is not part of the review flow at
all. New contributors and coding agents read this file as authoritative.

Before / after — bot review section

Before: a two-row table pairing Copilot with draft PRs and
CodeRabbit with ready PRs, a statement that auto-reviews are disabled
and both bots are triggered manually, a 5-step workflow built around
@copilot review, and a closing rule about never triggering Copilot on
a ready PR.

After: CodeRabbit is described as the automated reviewer that runs
on its own, followed by four behavior bullets — drafts are skipped;
review fires automatically on the draft to ready flip and on every
subsequent push; the walkthrough comment is commonly edited in place
rather than re-posted, so no new comment does not mean no new review;
a rate-limited CodeRabbit silently drops that review, and
@coderabbitai review after the window resets is the only case where a
manual trigger is appropriate. Copilot is covered in two sentences: not
part of the workflow, do not invoke it, and address any threads from a
third-party manual invocation like other reviewer feedback.

The table was dropped — with one bot and behavior rather than triggers
to describe, a bullet list carries it better.

CI list addition

Added an AI Validation entry (.github/workflows/ai-validation.yml)
between doc-linter and the Sphinx build. It cross-checks changed
docs/**/*.md against the VyOS CLI definitions in the vyos-1x source
tree for the corresponding branch and posts findings as inline review
comments plus a summary comment. It runs only when a PR touches Markdown
under docs/, and skips with a notice when the required repository
secrets are not configured or when the PR is a Mergify-authored
backport. The other four CI bullets were checked against
.github/workflows/ and scripts/doc-linter.py and are accurate as
written — the doc-linter scoping claim is confirmed by the comment at
scripts/doc-linter.py:28, and the Read the Docs preview check still
reports on PRs.

README.md points at AGENTS.md for "the Copilot/CodeRabbit bot review
workflow"; that phrase is updated to name CodeRabbit only, so the
pointer does not contradict the section it points to.

Review

Local CodeRabbit review against origin/rolling completed with 0
findings across both reviewed files (AGENTS.md, README.md).

Backport

circinus carries the same stale section and needs this change.
sagitta's AGENTS.md predates the bot-review section entirely and has
nothing to correct. Backport will be requested by post-merge comment.

🤖 Generated by robots

---

This is an automatic backport of pull request #2188 done by Mergify.

[mergify]

Cherry-pick of c9fb0c0 has failed:

On branch mergify/bp/circinus/pr-2188
Your branch is up to date with 'origin/circinus'.

You are currently cherry-picking commit c9fb0c0b.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   AGENTS.md
	both modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

Merge Protections

🔴 1 of 1 protections blocking · waiting on 🙋 you

	Protection	Waiting on
🔴	backport-conflict label must be absent to merge	🙋 you

🔴 backport-conflict label must be absent to merge

Waiting for

• label != backport-conflict

This rule is failing.

Block merge while the backport-conflict label is present. The label is auto-applied by the backport action on cherry-pick conflicts and must be manually removed after the conflict is resolved in the PR.

• label != backport-conflict