Fix typo, use consistent terminology

[andrewjradcliffe]

Submission Checklist

• Run tests: ./runCmdStanTests.py src/test
• Declare copyright holder and open-source license: see below

Summary:

make help-dev current prints bin/diagnostic as the token used to build bin/diagnose; if used, it produces an error. This PR fixes the aforementioned discrepancy and updates the terminology where it seemed appropriate.

Intended Effect:

make help-dev prints the correct token for building the diagnose utility.

How to Verify:

Self-evident.

Side Effects:

None.

Documentation:

None.

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company): Andrew J. Radcliffe

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[WardBrian]

Thanks