npm run grunt updated to npx grunt

[AdityyaX]

Resolves #6285

Changes:

Screenshots of the change:

PR Checklist

• npm run lint passes
• Inline documentation is included / updated
• Unit tests are included / updated

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[limzykenneth]

Hi @AdityyaX, the original issue only refers to instances in documentations where npm run grunt is used should be replaced with npx grunt. There is currently no plan to alias npm start as npx grunt (which in most cases probably confusing).