message: chore: update `npm` instructions in README
diff: @@ -89,7 +89,7 @@ Add the following section to your `package.json`:
  }
  ```
  -Finally, run `yarn test` or `npm run test` and Jest will print this message:
  +Finally, run `yarn test` or `npm test` and Jest will print this message:
  ```bash
  PASS ./sum.test.js
  