Improvement of installation instructions

[gmtiddia]

I installed NEST GPU using Ubuntu 22.04.4 LTS following the installation instructions step-by-step, noticing that there is an incompatibility between version 11.5 of the nvidia-cuda-toolkit and the default c++ compiler (c++11).

This is not a NEST GPU problem, as also shown here, and can be solved by installing a different version of the cuda toolkit (here for a list of the versions) following the installations instructions at the links provided.
I tested that, using c++11 and CUDA 12.4 version the problem is easily solved.

I think it would be useful to mention in the documentation that in certain cases, a specific cuda-toolkit version may be needed since the default nvidia-cuda-toolkit package installed by apt can lead to compatibility problems during compilation. Since this normally does not happen, maybe we can report this as a note in the CMake options page of the installation instructions.