Document how to Babel-transpile dependencies in node_modules too

[edmorley]

Currently Neutrino intentionally does not compile node_modules by default, since packages should be compiling down to ES5 themselves (even when using the module property in package.json). There is an increasing (and unfortunate) trend within the react-native packages to not do this - which resulted in confusion in #1046. (See facebook/create-react-app#1125 and facebook/create-react-app#3776 for more history on this area)

I believe the Neutrino default is currently the right thing to do (particularly since unlike CRA, it's easy to override), however it would be good to document how a project can enable the transpiling of node_modules - either via a single section on @neutrinojs/compile-loader or else a mention on all of the top-level presets.

The new section should include something like:
#1046 (comment)