Add documentation

[leakec]

Using SIHM

• [ ] Add documentation for regular function calls for geometry and materials
• [ ] Add documentation for non-standard calls for OBJ/MTL
• [ ] Add documentation for non-standard calls for GLSL. See #6. Also, include automatic time uniform and texture uniform conversions.
• [ ] Add documentation for non-standard scene background. See #11.
• [ ] Add documentation for SIHM section and show_stats and extra_modules. See #12.
• [ ] Add documentation for sihm CLI and its arguments.
  • Can we automate this by pulling click descriptions?
• [ ] Add documentation for Material* types, e.g., MeshPhysicalMaterial
  • Textures handled in non-standard way
  • Blending is handled in a non-standard way, e.g., just use THREE.NormalBlending as a string in the YAML file.
  • Colors handled in non-standard way.
  • Pass parameters as kwargs