Add instructions for ES6 modules for this page

[velara3]

On this page https://docs.npmjs.com/about-packages-and-modules/

Would a note about using ES6 import be appropriate?

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import

[kenshanta]

Once migrated from CJS to MJS module system

Reference:

https://github.com/npm/documentation/pull/899

[velara3]

Examples with both would be very helpful