Merge branch 'Stefan_add_README_files' into 'stats_include_e_pot_ext'

examples/CoolingHalo/README

examples/CoolingHalo/density_profile.py

examples/CoolingHalo/run.sh

examples/CoolingHalo/velocity_profile.py

examples/CoolingHaloWithSpin/README

examples/CoolingHaloWithSpin/density_profile.py

examples/CoolingHaloWithSpin/velocity_profile.py

examples/HydrostaticHalo/README

examples/HydrostaticHalo/density_profile.py

examples/HydrostaticHalo/hydrostatic.yml

examples/HydrostaticHalo/internal_energy_profile.py

examples/HydrostaticHalo/run.sh

examples/HydrostaticHalo/test_energy_conservation.py

examples/HydrostaticHalo/velocity_profile.py

src/potential/disc_patch/potential.h

src/potential/none/potential.h

src/potential/point_mass/potential.h

src/potential/softened_isothermal/potential.h