docs: Update restore-only cache documentation

[priya-kinthali]

Description:
This PR updates the restore-only cache example in docs/advanced-usage.md with a more detailed workflow using actions/cache/restore@v5.

Related issue:
#1545

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[Copilot]

Pull request overview

This PR updates the "Restore-Only Cache" example in docs/advanced-usage.md to address issue #1545, where the documented cache key did not match the actual key produced by setup-node (node-cache-${platform}-${arch}-${packageManager}-${fileHash}). The new example uses actions/cache/restore@v5 and computes a key matching the action's internal format.

Changes:

• Replaced the previous restore-only example with a snippet that builds the cache key as node-cache-${{ runner.os }}-${{ env.ARCH }}-npm-${{ hashFiles('**/package-lock.json') }}, including commented-out yarn/pnpm variants.
• Added an ARCH env var derived from a lower-cased runner.arch, and a step to read the package manager's cache path dynamically.
• Updated the trailing reference link to point to actions/cache/restore.

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