files/inp: refactored code generation

README.md

@@ -23,7 +23,7 @@ PyMCNP source code is accessable for contributions, suggestions, and bug reports
     pip install -e .
 
 
-If you plan to contribute, you should also enable `pre-commit`
+If you plan to contribute, you should also enable `pre-commit`:
 
     pip install pre-commit
     # cd into repo
@@ -42,6 +42,12 @@ After instaling `pytest`, test the `pymcnp` package by calling the following com
     cd PyMCNP
     python -m pytest
 
+## Metaprogramming
+
+To regenerate the autogenerated files in `files/inp/subclasses_cell_option`, `files/inp/subclasses_data`, and `files/inp/subclasses_surfaces`, run the following Python scripts:
+
+    parallel python3 {} ::: scripts/build_cell_options.py scripts/build_surfaces.py scripts/build_data.py
+
 ## Copyright and License
 
 For copyright and license infromation, see the `COPYRIGHT` and `LICENSE` files in the top level directory.