docs: add OpenClaw setup guide

[laolaoqi]

Closes #8

Adds a copy-paste-ready OpenClaw setup guide in docs/agents/openclaw.md with:

• Configuration instructions (YAML + env vars)
• API compatibility verification step
• Troubleshooting section

[GoDiao]

Thanks for the PR! One question before we merge: have you tested the plugins.free-way configuration shown here with a current OpenClaw build?

From a quick look at OpenClaw’s current docs, custom OpenAI-compatible endpoints seem to be configured through models.providers.<provider>.baseUrl / apiKey rather than a plugins block, so I want to avoid merging a snippet that might not work for users.

Also, could you confirm the example model? gpt-4 may not exist in a default Free-Way catalog unless a matching provider key/model mapping is available. A known Free-Way model such as llama-3.3-70b may be safer for the example.

[GoDiao]

Thanks again for the OpenClaw guide. This is a final follow-up before we close the stale PR.

Please update the example to the configuration shape supported by a current OpenClaw release (the current docs appear to use models.providers.<provider>.baseUrl / apiKey, rather than plugins.free-way) and use a model ID that is actually available in Free-Way, such as llama-3.3-70b. Please also note which OpenClaw version you tested.

If you can push a verified update by September 1, 2026, we'll review it. Otherwise, we'll close the PR to keep the queue current; a corrected version is welcome later.