docs: remove fake model (#2175)

packages/web/src/content/docs/docs/agents.mdx

@@ -533,7 +533,7 @@ For example, with OpenAI's reasoning models, you can control the reasoning effor
   "agent": {
     "deep-thinker": {
       "description": "Agent that uses high reasoning effort for complex problems",
-      "model": "openai/gpt-5-turbo",
+      "model": "openai/gpt-5",
       "reasoningEffort": "high",
       "textVerbosity": "low"
     }