Make the usage section more descriptive

[glacion]

Make the usage section more descriptive so that new people can get started faster.

Checklist

• [ ✔] Have you followed the guidelines for contributing?
• [ ✔] Have you checked that there aren't other open pull requests for the same feature you're adding?
• [ ✔] Have you run tests (pipenv run pytest) before sending this PR?
• [✔ ] Have you run linting (./lint.sh) before sending this PR?