Deprecate this module

[lazarljubenovic]

Can we at least add a message that the module is deprecated in the readme, possibly with a link to what we should use instead? A graveyard of useless rollup plugins doesn't do anybody any good.

[fent]

for anyone finding this issue and wondering, use rollup-plugin-node-externals

edit: sorry, it's https://github.com/ionic-team/rollup-plugin-node-polyfills

[JJ]

That one is even older...