docs: clarify POLYGON_WALLET_PRIVATE_KEY and OPENAI_API_KEY in env ex…

[JonesRoy3]

…ample

Clarifies what the Polygon wallet key and OpenAI key are used for in .env.example, with a small safety note on using low-value wallets.

---

[!NOTE] Adds clarifying comments and a safety note for POLYGON_WALLET_PRIVATE_KEY and OPENAI_API_KEY in .env.example.

• Docs:
  • Updates .env.example:
    • Clarifies purpose of POLYGON_WALLET_PRIVATE_KEY and OPENAI_API_KEY.
    • Adds safety note to use a low-value wallet for testing.

^{Written by Cursor Bugbot for commit 43bd4eb84eec87a88212ef7562aae16669ff67cc. This will update automatically on new commits. Configure here.}