Improved documentation for GPU deployments

[clemekay]

From the 05/07/2025 document "MC/DC Plans Through the End of CEMeNT" :

Extending the documentation we already have to include FAQs, and a trouble shooting guide. Numba patching for older versions of Numba, building mpi4py from source, correct module environments, building with conda instead of pip, and batch scripts for flux, slurm, and lsf.