Fix typos and improve documentation clarity

[hunterhogan]

I focused on the CLI help text.

Description

Replace this text with a description of your changes, indicating whether
it is a bug fix, enhancement, etc. and which general area(s) are affected
(documentation, specific tool, group of tools, tests, etc.).

If the contribution closes (fixes, resolves) a specific open
issue, please link
the issue.

Checklist:

• I have followed the Contribution Guidelines
• I have added test code and data to prove that my code functions correctly
• I have verified that new and existing tests pass locally with my changes
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation

[skef]

LGTM

[skef]

You have some flake8 problems -- see the failing test for reference.