Document current purl-spec CI workflows

[mjherzog]

The CI workflows files are:

File	Description
Makefile	top-level script
github/workflows/generate-index-and-docs.yml
etc/scripts/doc-generation.txt	Obsolete with documentation published to the website - to be deleted
etc/scripts/format_json.py
etc/scripts/generate_index_and_docs.py
etc/scripts/git-split-file.sh	One-time use for initial mega-PR to create schema and test files
etc/scripts/purl_test.py	Generated by Makefile/gencode command
etc/scripts/purl_type_definition.py	Generated by Makefile/gencode command
etc/scripts/purl_types_index.py	Generated by Makefile/gencode command
etc/scripts/pyproject.toml	Configuration for Python ruff tool (linter and code formatter)
etc/scripts/remove_duplicate_tests.py	Might be for temporary use during initial creation of test files
etc/scripts/requirements.txt	Python dependency manifest - not sure why packageurl-python is included

The task is to document the contents of each file and summary of how they are used.

[mjherzog]

@johnmhoran The table above is to provide a starting point for documenting the files. At some point we will want to create a markdown document in the repo perhaps in a new folder like docs/internal or ?