Update knowledge model settings

Example request

{
  "system_message": {
    "personality": "You are an assistant for question-answering tasks.",
    "responses": "Be concise! You can give additional note or explanation about the problem and the solution you give if necessary, but keep it short. Be sure to answer the question directly instead of only giving explanatory notes!"
  },
  "documents_access": {
    "webhook_url": "https://example.com/webhook-endpoint"
  }
}