Updated cql-to-elm instructions in README.md

[sorliog]

Pull requests into cql-execution require the following. Submitter and reviewer should ✔ when done. For items that are not-applicable, mark "N/A" and ✔.

CDS Connect and Bonnie are the main users of this repository. It is strongly recommended to include a person from each of those projects as a reviewer.

Summary

Instructions for translating CQL to ELM in README.md are out of date with clinical_quality_language. This update changes the documentation to use the cql-to-elm-cli executable instead of the cql-to-elm library.

Submitter:

• [x] This pull request describes why these changes were made
• [ N/A ] Code diff has been done and been reviewed (it does not contain: additional white space, not applicable code changes, debug statements, etc.)
• [ N/A ] Tests are included and test edge cases
• [ N/A ] Tests have been run locally and pass
• [ N/A ] Code coverage has not gone down and all code touched or added is covered.
• [ N/A ] Code passes lint and prettier (hint: use npm run test:plus to run tests, lint, and prettier)
• [ N/A ] All dependent libraries are appropriately updated or have a corresponding PR related to this change
• [ N/A ] cql4browsers.js built with npm run build:browserify if source changed.

Reviewer:

Name:

• [ ] Code is maintainable and reusable, reuses existing code and infrastructure where appropriate, and accomplishes the task’s purpose
• [ ] The tests appropriately test the new code, including edge cases
• [ ] You have tried to break the code

[cmoesel]

Thanks, @sorliog. It looks like npm audit is failing CI, but since this is a documentation-only PR, I don't think that it's fair to expect you to address npm audit issues. So... I will merge. Thanks again!