Document temperature experiments using Riteway ai

In docs/riteway-ai.md, add complete documentation of Riteway ai features and

• please include just a minimal usage guide in the readme and link to the rest of the docs from there - make sure it comes AFTER basic Riteway usage examples/general Riteway getting started guide In the README.
• Add the following section to the riteway-ai docs:

Configuring Model and Temperature (OpenCode)

Most agent harnesses don't expose temperature settings. If you need
temperature control for Riteway AI evals, use OpenCode with a custom
agent config.

1. Create the agent file

Create .opencode/agents/riteway.md in your project root:

---
description: Riteway AI eval agent
mode: primary
model: anthropic/claude-sonnet-4-6
temperature: 0.2
---

2. Configure the Riteway agent

In your Riteway config, reference the agent by filename (without extension):

{
  "opencode": {
    "command": "opencode",
    "args": ["run", "--agent", "riteway", "--format", "json"],
    "outputFormat": "ndjson"
  }
}