Finalize new version of Pressbooks coding standards

[SteelWagstaff]

As a developer at Pressbooks, I want to have a clear set of coding standards that are used and applied to all repos we maintain to increase the consistency, quality, and security of the code we maintain.

Our current coding standard are here: https://github.com/pressbooks/coding-standards. They are basically Human Made's coding standards with a few tweaks. In 2022, Ricardo wrote a proposal for our team to consider re: coding standards. It was never adopted. Our current development team should decide on the standards we wish to use and introduce these standards to each of the repos we maintain, as/when we next work on each repo.

In our newest projects (pressbooks-network-catalog and pressbooks-multi-institution), we are not using our existing coding standards or build tools. See pressbooks/pressbooks-build-tools#313

[SteelWagstaff]

Some models our team likes: https://10up.github.io/Engineering-Best-Practices/ + https://engineering.hmn.md/ + https://nationaluniversitysystem.github.io/dev-knowledge-hub/#/