Docs: Tools become FunctionToolset

[HamzaFarhan]

It might be worth mentioning in the docs that all tools get gathered into a FunctionToolset internally
Makes it easier to frame things and also to answer the question "Should I use tools= or toolsets=?"
I would make a PR, but I'm sure someone else or even claude can better articulate this.

[DouweM]

@HamzaFarhan Good idea, I think that can be a single sentence at the end here:

pydantic-ai/docs/tools.md

Line 15 in 69e90bc

For more advanced use cases, the [toolsets](toolsets.md) feature lets you manage collections of tools (built by you or provided by an [MCP server](mcp/client.md) or other [third party](#third-party-tools)) and register them with an agent in one go via the [`toolsets`][pydantic_ai.Agent.__init__] keyword argument to `Agent`.

Feel free to submit a PR, with help from Claude if you like :)