Add documentation to build GauXC

[awvwgk]

• add installation instructions for GauXC library
  • with OpenMP
  • with MPI
  • with CUDA
• list dependencies of GauXC (libtorch, ExchCXX, IntegratorXX, HDF5, HighFive, nlohmann_json, gau2grid, BLAS, ...)
• add instructions for obtaining checkpoints from Huggingface
• provide minimal example on how to use GauXC Skala library
• add instructions on using s-dftd3 library for evaluating dispersion correction for Skala

[kjh-giesbertz]

There seems to be something wrong in the cartesian version:

mol = gto.M(atom="He 0 0 0; Ne 0 0 2.0", basis="def2-qzvp", unit="Bohr", spin=0, cart=True)
gives
EXC (ref) = -1.35529407216016e+01
EXC (calc) = -1.33526784882510e+01
EXC Diff = -1.47762937552981e-02
| VXC (ref) |_F = 2.47705806355824e+01
| VXC (calc) |_F = 1.81479250598974e+01
RMS VXC Diff = 9.16350291581032e-02

mol = gto.M(atom="He 0 0 0; Ne 0 0 2.0", basis="def2-qzvp", unit="Bohr", spin=0, cart=False)
gives
EXC (ref) = -1.35529277410941e+01
EXC (calc) = -1.35529447345960e+01
EXC Diff = -1.25386206588653e-06
| VXC (ref) |_F = 1.65203073321537e+01
| VXC (calc) |_F = 1.65202505202321e+01
RMS VXC Diff = 1.28538169430761e-04

[kjh-giesbertz]

The file name lacks a dash compared what is used later to inspect the content

Suggested change

	write_gauxc_h5_from_pyscf("He_def2svp.h5", mol, dm=dm, exc=exc, vxc=vxc)
	write_gauxc_h5_from_pyscf("He_def2-svp.h5", mol, dm=dm, exc=exc, vxc=vxc)

[kjh-giesbertz]

The file name lacks a dash compared what is used later to inspect the content

Suggested change

	ref_file = He_def2svp.h5
	ref_file = He_def2-svp.h5