Docs: align v0.25 guide on UTF-8, experimental apm run, and LSP overview

[c-dollas]

Affected version

APM CLI 0.25.0 (d73e6ac) and the microsoft/apm/packages/apm-guide#v0.25.0 package.

Verified documentation gaps

1. The guide presents ASCII-only authoring as a requirement, but current APM parsing and validation support UTF-8 content. Please narrow this to a portability recommendation if that is the intended guidance.
2. The apm run guidance does not identify the command as experimental, although the installed 0.25.0 CLI exposes it as an experimental surface. Please add the stability caveat so automation does not treat the interface as stable.
3. The guide overview's target/feature summary omits LSP even though LSP support is documented elsewhere in the same version. Please include LSP in the overview or link to the authoritative LSP section.

Scope note

I independently checked two adjacent claims and am intentionally not reporting them as defects: singular target: is a valid manifest form, and LSP is documented outside the overview. No deployed guide files were modified locally.

Expected result

The v0.25 guide should distinguish requirements from recommendations, label experimental CLI surfaces, and keep the overview consistent with the detailed feature documentation.