docs: add instruction for ollama auto config cli

[arian81]

What does this PR do?

Adds instructions about ollama launch opencode to the docs.

How did you verify your code works?

Ran the docs to make sure the changes look proper.

Fixes #10768

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Related PRs:

1. PR feat(provider): auto-detect Ollama context limits #10758 - feat(provider): auto-detect Ollama context limits

   • Related to ollama auto-detection functionality, though this focuses on context limits rather than CLI instructions

2. PR feat(opencode): add auto model detection for OpenAI-compatible providers #8359 - feat(opencode): add auto model detection for OpenAI-compatible providers

   • Related to auto-detection for ollama and other providers

3. PR docs(web): clarify custom provider config scope and baseURL #9612 - docs(web): clarify custom provider config scope and baseURL

   • Related documentation about provider configuration

These are not exact duplicates but are related to ollama functionality and configuration. PR #10758 appears to be the closest in terms of recent ollama auto-detection work, though it addresses a different aspect (context limits vs. CLI instructions).