docs: publish ClawHub install path

[fancyboi999]

Summary

• replace the pre-release ClawHub wording with the live package link
• keep the documented install command pinned to the published goofish-cli==0.3.0 runtime

Verification

• ClawHub package openclaw-goofish@0.3.0 is published and installable
• registry install resolves the exact published tarball SHA-256
• openclaw plugins inspect goofish --json reports format=bundle, skills + MCP capabilities, and no diagnostics
• pnpm dlx npm@10.9.2 test — 3 passed
• pnpm dlx npm@10.9.2 run pack:check — 33 files
• sensitive identifier scan and git diff --check passed