docs(skill): clarify standalone discovery description

[yunze7373]

Summary

• simplify the standalone Skill frontmatter description around its core memory, continuity, TODO, expense, and diagnostics workflows
• bump only the standalone Skill patch from 1.1.10 to 1.1.11 and add the matching changelog entry

Evidence and validation

• ClawHub baseline: xmemo 1.1.10, moderation clean, source manifest verified by promote-release.mjs
• public origin/main baseline: 7841444
• candidate gate: passed (3 allowlisted files, +10 lines, next patch 1.1.11)
• npm run lint: passed
• focused tests: node --test test/xmemo-skill.test.js test/xmemo-standalone-skill.test.js (31/31 passed)
• npm run pack:dry-run: passed

Risk boundary

Docs/discoverability wording only. No changes to runtime behavior, network requests, authentication, credentials, scopes, service/API, deletion, privacy, dependencies, npm metadata, or release automation. skill-card.md is unchanged.