Fix docs link-validator failures from stale experiments page URLs

[Copilot]

The docs deploy workflow failed in link validation because several pages still referenced removed experiments routes (/guides/... and /reference/...). This PR updates those references to the current /practices/... routes so the docs build can resolve all internal links.

• Scope of fix

  • Updated stale experiments links in:
    • docs/src/content/docs/practices/experiments-specification.md
    • docs/src/content/docs/reference/artifacts.md
    • docs/src/content/docs/reference/forecast-specification.md
    • docs/src/content/docs/reference/glossary.md

• Route corrections applied

  • /gh-aw/guides/experiments/ → /gh-aw/practices/experiments/
  • /gh-aw/reference/experiments-specification/ → /gh-aw/practices/experiments-specification/

• Representative change

  - See [A/B Experiments](/gh-aw/guides/experiments/)
  + See [A/B Experiments](/gh-aw/practices/experiments/)

[Copilot]

Pull request overview

Updates internal documentation links to reflect the current Experiments documentation routes, resolving link-validator failures in the docs deploy workflow caused by stale /guides/... and /reference/... URLs.

Changes:

• Replaced stale /gh-aw/guides/experiments/ links with /gh-aw/practices/experiments/.
• Replaced stale /gh-aw/reference/experiments-specification/ links with /gh-aw/practices/experiments-specification/.
• Updated references consistently across glossary, artifacts reference, forecast specification, and the experiments specification page.

Show a summary per file

File	Description
docs/src/content/docs/reference/glossary.md	Updates glossary cross-links for A/B Experiments and the experiments specification to the /practices/ routes.
docs/src/content/docs/reference/forecast-specification.md	Updates both “out of scope” and normative reference links to the experiments specification /practices/ route.
docs/src/content/docs/reference/artifacts.md	Updates the A/B Experiments link in the experiment artifact section to the /practices/ route.
docs/src/content/docs/practices/experiments-specification.md	Updates “Latest Version” link to the current /practices/experiments-specification/ route.

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• Files reviewed: 4/4 changed files
• Comments generated: 0