docs(llms.txt): update dirhtml-skip rationale after .md pivot

The previous comment on `_write_llms_txt` (and on the LLM-Facing Files
section in CLAUDE.md) justified the `dirhtml` skip by claiming the
template's `.html` URLs wouldn't resolve under `dirhtml` output. That
became stale after [#1874@5fe7f9ad](https://github.com/vyos/vyos-documentation/pull/1874/commits/5fe7f9ad) (and parity commits on
[#1876](https://github.com/vyos/vyos-documentation/pull/1876)/[#1903](https://github.com/vyos/vyos-documentation/pull/1903)) pivoted the curated template to `.md` URLs —
`_copy_md_sources` puts `.md` files at their source-relative paths
regardless of builder, so the rendered llms.txt would actually resolve
fine under `dirhtml` now.

The real reason we skip `dirhtml` is simpler: production publishes
only via the `html`/`readthedocs` builders, and we don't render
llms.txt for builds we don't ship. Local `make dirhtml` is a developer
convenience, not a publish target.

Reword the conf.py comment and the CLAUDE.md section to say that
plainly. No code-behavior change.

Addresses Copilot review feedback on PR #1874 (3 threads on docs/conf.py,
docs/_templates/llms.txt.j2, and CLAUDE.md flagging the inconsistency).

\xf0\x9f\xa4\x96 Generated by [robots](https://vyos.io)

1 files changed, 6 insertions, 4 deletions

diff --git a/docs/conf.py b/docs/conf.py
index 26ce346c..dddb78fe 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -267,10 +267,12 @@ def _write_llms_txt(app, exception):
     ``release``, and writes ``<outdir>/llms.txt``. ``llms-full.txt`` is
     handled separately by the ``sphinx_llms_txt`` extension.
     """
-    # Skip dirhtml: the curated template encodes `.html` URLs (e.g.
-    # `quick-start.html`), which don't exist under `dirhtml` output
-    # (`quick-start/index.html`). Production publishes via the html /
-    # readthedocs builders, so dirhtml output would just be misleading.
+    # Skip dirhtml: production publishes via the `html` / `readthedocs`
+    # builders only. The `.md` links in the curated template do
+    # actually resolve under `dirhtml` (`_copy_md_sources` puts `.md`
+    # files at their source-relative paths regardless of builder), but
+    # we still don't render llms.txt for builds we don't ship — local
+    # `make dirhtml` is a developer convenience, not a publish target.
     if exception is not None or app.builder.name not in (
             'html', 'readthedocs'):
         return