Update quickstart package install path

[HwangJohn]

Summary

• update public quickstart to include published package install paths
• document uvx --from llmwiki-serve==0.2.0 and npm exec --package llmwiki-agent-bridge@0.1.0

Spec / ADR

• No separate spec/ADR: documentation-only update that reflects already-published package paths.

Contract impact

• None.

Validation

• npm run check
• LLMWiki projection smoke over llmwiki-docs/docs; quickstart.md appears in query evidence for package quickstart terms.

LLMWiki/docs update status

• Canonical docs file updated: docs/quickstart.md.

Data safety review

• No credentials, private endpoint URLs, private logs, or local absolute paths were added.
• Uses placeholder /path/to/your/wiki only.