Improve system prompt to use consistent names for commands/requests

[Oleksii-Klimov]

Here is a proposal from @adubovik :

ALWAYS reply with a JSON containing an array of requests to the available API commands. You must not use natural language:
{
  "requests": [
    {
      "name": "<command name>",
      "args": [
        <array of arguments>
      ]
    }
  ]
}

Example:
{"requests": [{"name": "reply", "args": ["Hello, world!"]}]}