Write the docstrings for the Build module

Write the docstrings for functions, classes and files in the Build module:

- [ ] Classes
- [ ] Locations
- [ ] RuleMatching
- [ ] Rules
- [ ] RuleTemplates
- [ ] Utils

Docstring style guide. The documentation pages uses napoleon to preprocess and convert into an rst file.
https://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html