Corrected docs for plan command

[jlamoree]

It appears that there was a copy 'n' paste error in the docs. This is a single-line change that should cause the docs to have the correct command help output for plan, rather than new.

• Have you followed the guidelines in our Contribution Requirements?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Does your submission pass tests?
• Have you linted your code locally prior to submission?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?
• Have you updated documentation, as applicable?