docs: fix import example for ES 2015 at: loading-into-nodejs.md

[elizatlawy]

The import as described in the documentation does not work:

import AdvancedFormat from 'dayjs/plugin/advancedFormat' // ES 2015 It should be:

import AdvancedFormat from 'dayjs/plugin/advancedFormat.js' // ES 2015

[iamkun]

Thanks, I see the related issue. Can you please provide a re-production instruction so that I can check it in depth?

[elizatlawy]

@iamkun try to import it:

import advancedFormat from 'dayjs/plugin/advancedFormat';