docs: add stricter validation options (#12998)
## Summary
Applying the same change as done in
https://github.com/astral-sh/uv/pull/6096. Note that in `uv` repository,
this [broke the docs
build](https://github.com/astral-sh/uv/pull/6096#issuecomment-2290151150)
because `anchors` is `mdkocs` 1.6+ only, and insiders used 1.5.0 while
public dependencies used 1.6.0, but in this repository, both use 1.6.0
([public](https://github.com/astral-sh/ruff/blob/049cda2ff37bcae59f7dae9af6a453075c76e635/docs/requirements.txt#L3),
[insiders](https://github.com/astral-sh/ruff/blob/049cda2ff37bcae59f7dae9af6a453075c76e635/docs/requirements-insiders.txt#L3)),
so this should not be an issue to have in the template.
Contrarily to `uv` repository, no violations were reported here, but
this could prevent adding some in the future.
## Test Plan
Local run of the documentation + `mkdocs build --strict`.
