Incorrect webpack configuration guidelines

[kaytcat]

The documentation for adding webpack configuration (https://github.com/redfin/react-server/blob/master/docs/guides/react-server-cli.md#webpack-options) is using camel case for defining the webpackConfig option which makes sense since the rest of the options are camel cased. However, I've found the option only works when written as "webpack-config".

I think maybe the code could be updated to use all camel cased options or at least the guide could reflect the correct options.

[feychou]

Related a23199e

[gigabo]

Ugh. Thanks for reporting @kaytcat.

#783 would resolve this.