docs(samples): list joke-agent samples in samples README

[apetraru-uipath]

What changed?

The joke-agent and joke-agent-decorator sample directories already exist under samples/, but they were not listed in the samples/README.md index. This PR adds index entries for both so they are discoverable from the samples overview:

• Joke agent — LangGraph agent generating family-friendly jokes, with a middleware-based guardrails stack (PII detection, prompt injection prevention, content validation) and HITL escalation on PII in the input.
• Joke agent (decorator-based guardrails) — same use case demonstrating the unified @guardrail decorator applied without a middleware stack.

Docs-only change; no code was modified.

How has this been tested?

Verified the two directories exist on main and that the README links resolve to them. Markdown-only change, no automated tests apply.

Are there any breaking changes?

• None

[Copilot]

Pull request overview

Updates the samples index to make the existing joke-agent examples discoverable from the samples/ overview documentation.

Changes:

• Adds an index entry for the joke-agent sample with a brief description of its guardrails + HITL behavior.
• Adds an index entry for the joke-agent-decorator sample highlighting the unified @guardrail decorator approach.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud