Editorial fixes for various rxcoeff params

[keckler]

What is the change?

This is a continuation of #1498. I wish I had caught everything in that single PR, but alas I did not.

I only do the following:

• change the units strings on a handful of parameters in which there was a stray parenthesis at the end
• Make the capitalization and punctuation consistent across rxcoeff param descriptions (didn't change the param names themselves)

No physics changes at all.

Why is the change being made?

Cleanliness.

---

Checklist

• This PR has only one purpose or idea.
• Tests have been added/updated to verify that the new/changed code works.

• The code style follows good practices.
• The commit message(s) follow good practices.

• The release notes (location doc/release/0.X.rst) are up-to-date with any important changes.
• The documentation is still up-to-date in the doc folder.
• No requirements were altered.
• The dependencies are still up-to-date in pyproject.toml.

[keckler]

Give me a second to also update the parameter descriptions to have reasonable formatting.

[keckler]

Okay, this is ready to go now. I also made the capitalization and ending punctuation consistent between all the rxcoeffs param descriptions.

[keckler]

Fix the one parameter that has "dk/k/k" instead of "\Deltak/k/k"

EDIT: Done.