Document the published BabelDOC 0.6.4+gloss.4 runtime

[SunChJ]

What changed

• update the runtime manifest example to the published 0.6.4+gloss.4 release
• record the real release tag, asset URL, digest, size, and nested executable path
• update the managed-runtime directory example

Why

The failed 0.6.4+gloss.3 runtime was never published. Gloss now consumes the signed stable manifest for the successfully published 0.6.4+gloss.4 runtime, so the release documentation included in the upcoming v0.8.0 tag should match the actual public artifact.

Validation

• downloaded the stable manifest through the public releases/latest/download URL
• verified its detached Ed25519 signature with Gloss's pinned BabelDOC public key
• verified the manifest and signature GitHub artifact attestations
• git diff --check