More instructions about exclude_from_externals

[Shawn hu]

Hi @halt-hammerzeit,

Thanks for this awesome lib first.

I ran into a problem when my app requires some css file from a library in node_modules, it has taken me quite some time to figure out exclude_from_externals can deal with this

(I had to look in to server configuration.js's source code, seen your comments there)

From the docs I read, I can understand its about webpack, people shall learn this setting from webpack docs, but still a little more instructions can make people aren't webpack experts like me 's life easier

maybe something like:

When requiring non-js files from node_modules, you must mark them as non-external so webpack buildings for server side can process them

[Nikolay]

Hello.
exclude_from_externals option is described in the README, but it is only described for the use case of JS files.
I didn't think that someone would use it for CSS.
I have updated the README with your suggested instructions

[Shawn hu]

Looks great to me, thanks