Reword invalid formatting error.

[Spudds]

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• [x] I agree to the Contribution Guidelines and to the Code of Conduct
• [x] I tested my code and I verified it's working to the best of my ability
• [x] I checked if my code doesn't violate the styleguide with npm test

Describe your pull request

Makes the invalid formatting error clearer for new Custodians so they can understand what part of the command they have got wrong.

Why is this change needed?

So new Custodians have a clearer explanation as to why the way they did the command didn't work.

Does your pull request solve an open issue? If yes, please mention what one