docs: the quickstart on the home page could not be run

[tactino]

The quickstart on the home page could not be run as written.

The gap

It opens two terminals and runs plugrl-run-server and plugrl-run-env-client, with no installation step anywhere above them. Neither package is on PyPI - user_guide/get_started.md says so and gives the clone-and-uv sync recipe - but the home page only links to that page from the very bottom, under "Next steps". A reader following the front page in order meets command not found.

The four lines from Get Started now sit above the terminals, with a pointer to the full page for the other environment extras. Copied from that page rather than rewritten, so the two cannot drift apart into two different recipes.

Two smaller things, in both languages

• The page led with a sentence any framework could write - "an RL infrastructure for distributed experiments with a clean split" - while the one fact worth arriving for sat 60% of the way down. A line after the intro now says a full-size pi0.5 ran end to end and that the reinforcement learning result is negative, and links to that section. The quickstart keeps its place at the top: people come to documentation for the commands.
• The opening note was a bare blockquote while the rest of the page uses Material admonitions. It is now !!! note, like the others.

Anchors

#a-real-vla-end-to-end in English. In Chinese the slugifier drops CJK, so headings there get _1, _3, and so on; that heading keeps its Latin letters and becomes #vla. Both were read out of the built HTML rather than guessed:

site/index.html:    id="a-real-vla-end-to-end"
site/zh/index.html: <h2 id="vla">真实 VLA，端到端

mkdocs build --strict passes.