docs: clarify Pi provider-prefixed model configuration (#55865)

* Initial plan

* docs: add Pi model prefix examples

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Author: Copilot

docs/src/content/docs/setup/quick-start.mdx

@@ -154,7 +154,7 @@ This will take you through an interactive process to:
     To avoid a long-lived key, configure [Google Workload Identity Federation](/gh-aw/reference/auth/#google-workload-identity-federation-wif).
   </TabItem>
   <TabItem label="Pi">
-    Pi chooses authentication from the provider prefix in `model:`. It uses Copilot authentication by default, `ANTHROPIC_API_KEY` for `anthropic/...`, and `CODEX_API_KEY` or `OPENAI_API_KEY` for `openai/...` and `codex/...`.
+    Pi chooses authentication from the provider prefix in `model:`. It uses Copilot authentication by default, `ANTHROPIC_API_KEY` for `anthropic/...`, and `CODEX_API_KEY` or `OPENAI_API_KEY` for `openai/...` and `codex/...`. For example, use `model: copilot/gpt-5.4`, `model: anthropic/claude-sonnet-5`, or `model: openai/gpt-5`.
 
     Pi also requires `tools.github.mode: gh-proxy` and `tools.cli-proxy: true`. Follow [Using Pi with GitHub Agentic Workflows](/gh-aw/engines/pi/) for the complete setup.
   </TabItem>