remove internal macro and todo from readme

[leoebfolsom]

Closes #64

Description & motivation

This PR addresses two separate issues:

• https://github.com/dbt-labs/dbt-audit-helper/issues/64
• The compare_column_values_verbose part of https://github.com/dbt-labs/dbt-audit-helper/issues/61

Note that I explained the context of compare_column_values_verbose in this comment.

tl;dr is that I'm hoping we can keep it as an internal macro to make the code easier to understand; but regardless, it should be removed from the readme to reduce readme overwhelm. compare_column_values_verbose is an internal macro used by another macro in the package itself, and doesn't really need to be exposed to the user (and certainly not in the readme).

Checklist

• [x] I have verified that these changes work locally
• [x] I have updated the README.md (if applicable) (definitely applicable!)
• [x] I have added tests & descriptions to my models (and macros if applicable)

[leoebfolsom]

@graciegoheen I'm not sure if I'm able to officially request a review, but I thought you might want to see this one and avoid any duplicate efforts 🙏