docs: port v0.1.0 doc restructure from main (PR #473)

[pmoutsias-amd]

Summary

Ports the doc changes from #473 (merged to main) onto the 0.1.0 docs, minus
every description of functionality that shipped after the 0.1.0 cut.

The 0.1.0 branch has no rocm remote, no rocm install sdk --devel toolchain
concept, no rocm services list --json, and none of the prune-wait or
storage-report additions. The README and docs/vllm.md prose describing those
stays out, so this is a curated port rather than a cherry-pick of #473's
commits.

README

• Split the install sdk prose into subsections and add a ##### ROCm 10 and newer heading. The --devel subsection is omitted because the flag does not
  exist on this branch.
• Editorial: the approval-prompt sentence, the
  --approve-replacing-active-default and install-location line wraps, the
  update table's Effect -> Description rename with the --apply "never
  prompts" wording, the "Nothing about this happens on its own" paragraph, and
  the em-dash -> period fix in the qwen serve paragraph.

vLLM topic

• docs/vllm.md: heading promotion, ROCm CLI naming throughout, the env-var
  placeholder rewording, and the Related resources titled links. The
  --devel source-build paragraph is omitted.
• Adds docs/rocm-docs/engines/vllm.md, transcluding docs/vllm.md.
• Regroups index.rst and _toc.yml.in: Demos under Getting started, and
  Commands -> Use ROCm CLI with Command reference before vLLM adapter.
• Adds the Command reference intro sentence and the getting-started copy
  comment, and swaps installation.md's vLLM link for the new page.

CI

• Adds docs/vllm.md to the docs: path filter. The new page transcludes it,
  so a later edit to that file alone must not skip the -W docs build.

Test plan

• Sphinx docs build (-W) passes with no warnings
• New vLLM adapter page renders in the nav
• Every :start-after: anchor in the including pages still matches
  README.md exactly once

Docs-only change: no CLI behavior changes, so no test scenario is needed. The
-W docs build is what validates it.