Outdated docs for `generate_control_function`

[Azercoco]

Describe the bug 🐞

As of 9.79.1, the change of behaviour of generate_control_function has not been documented.

Expected behavior

From #3269, the generated function from generate_control_function expect MTKParameters if split=false is not passed as argument. Passing p as a Vector{Float64} results in some strange undefined behaviour.

The documentation does not reflect this behaviour. Moreover, the example given luckily works with a Vector{Float64}.

The documentation should be updated and a maybe an explicit check should be done to throws an error if a Vector{Float64} is passed when splithas not been set to false.

[ChrisRackauckas]

I think this is covered in the v10 docs overhaul