draft: Use only asr/mt instead of nlp as usage prefix

[jamesrkiger]

Checklist

1. If you've added code that should be tested, add tests
2. If you've changed APIs, update (or create!) the documentation
3. Ensure the tests pass
4. Make sure that your code lints and that you've followed our coding style
5. Write a title and, if necessary, a description of your work suitable for publishing in our release notes
6. Mention any related issues in this repository (as #ISSUE) and in other repositories (as kobotoolbox/other#ISSUE)
7. Open an issue in the docs if there are UI/UX changes

Description

Describe the outcome of your work here. A non-programmer who is familiar with KoboToolbox should be able to understand what you've written; more technical details can be added to the Notes section below. You may omit this if the title alone provides enough information. Both the title and this description will be published in the release notes on our forum.

Notes

Describe what you've changed and why. This should allow the reviewer to understand more easily the scope of the PR. It's good to be thorough here.

Related issues

Fixes #ISSUE
Blocked by #ISSUE
Part of #ISSUE