Pull Changes from develop for documentation updates

[mhogan-nwra]

Topic

Add documentation updates that reflect the intended use cases and migration to envector from nvector.

Steps

1. Include an example for use

No changes to the API were introduced.

2. Add a note to CHANGELOG.rst about the changes

I do not believe this is required. The last item in version 0.3.1 explains enough.

Expand documentation on the reasons for the existence of envector.

3. Update the author list in AUTHORS.rst if applicable

Not necessary

4. Ensure that all checks passed (current checks include GitHub Actions)

Ran nox and all versions (3.9 - 3.12) passed.

[mhogan-nwra]

Decision

This pull request has been accepted and will be merged.

Reason

All GitHub Actions CI passed and no merge conflicts are present.