Outdated documentation regarding axialFlowTurbineALSource

[MakisH]

The documentation of the cfd-turbine case states:

openfast-adapter/cases/cfd-turbine/README.md

Line 14 in be75919

Remark: For future experiments, the OpenFOAM library [turbinesFoam](https://github.com/turbinesFoam/turbinesFoam) may be interesting to represent wind turbines using the actuator-line method. The necessary system files are included in this setup but not activated.

However, OpenFOAM (at least v2312) seems to complain with the current setup:

--> FOAM FATAL IO ERROR: (openfoam-2312 patch=240220)
Unknown fvOption type axialFlowTurbineALSource

The system/fvOptions also has:

turbine
{
    type            axialFlowTurbineALSource;
    active          on;

@LeonardWilleke What was the deactivated alternative meant to be?

Installing turbinesFoam and enabling the library in system/controlDict works.