docs(agents): doc-linter is in-repo, scoped to docs/ — fix stale references

Two stale claims flagged by Copilot in PR #2014 (one comment marked the
other as 'same issue earlier in the file'):

- '## Lint' (L40-45): said 'vyoslinter (doc-linter.py from the
  vyos/.github repo, via the lint-doc.yml workflow) on changed files
  only'. The cross-repo dependency was dropped in 1bf386e — the
  linter is now scripts/doc-linter.py in this repo, invoked from
  .github/workflows/lint-doc.yml.
- '## CI' (L290-292): same stale claim in bullet form.

Also reflect 65a8e9f's scoping decision: the linter applies only to
files under docs/. Repo-root meta files (README.md, AGENTS.md,
.github/copilot-instructions.md) are explicitly out of scope, since
they are project meta rather than published documentation and don't
need to obey docs-publication conventions (80-char wrap, RFC IP
rules, suppression markers). Mention that exclusion in the CI bullet
so contributors know the linter won't catch issues there.

1 files changed, 11 insertions, 9 deletions

diff --git a/AGENTS.md b/AGENTS.md
index 32c5885d..f445a7c7 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -37,12 +37,12 @@ Output: `docs/_build/html/`.
 
 ## Lint
 
-The repo doesn't ship a local lint config or pin a linter binary. CI runs
-`vyoslinter` (`doc-linter.py` from the `vyos/.github` repo, via the
-`lint-doc.yml` workflow) on changed files only — see the CI section
-below. For local checks, manually grep for the rules in
-[Source conventions](#source-conventions) (line length, address space,
-suppression markers).
+The repo doesn't ship a local lint config or pin a linter binary. CI
+runs `scripts/doc-linter.py` (in-repo, invoked from
+`.github/workflows/lint-doc.yml`) on changed files only, scoped to
+`docs/` — see the CI section below. For local checks, manually grep
+for the rules in [Source conventions](#source-conventions) (line
+length, address space, suppression markers).
 
 ## Branches and versions
 
@@ -287,9 +287,11 @@ serves and crawlers skip the redirect hop.
 
 ## CI
 
-- **vyoslinter** (`doc-linter.py` from the `vyos/.github` repo, run
-  via `lint-doc.yml`) — line length and IP rules, on changed files
-  only.
+- **doc-linter** (`scripts/doc-linter.py` in-repo, invoked via
+  `.github/workflows/lint-doc.yml`) — line length and IP rules, on
+  changed files under `docs/` only. Repo-root meta files
+  (README.md, AGENTS.md, `.github/copilot-instructions.md`) are out
+  of scope.
 - **Sphinx build** — runs on Read the Docs for every PR; preview URL
   appears as a check.
 - **CLA check** — contributors must sign the VyOS CLA before merge.