Fix typo and readme bug

[ruelasb]

On line 70 the production server can not find the bundle.js
file because webpack.config.js pushes the bundle.js into the
/public path. The result is a blank page because the
server has not been set up with the proper path of /public.
The Webpack configuration must be applied after the public
directory has been created on line 80 or once the server has
been configured to read from the public directory.

[ruelasb]

If it makes it easier to understand I will do some further explanation the changes. Basically when the following instructions are stated in the readme.md file

Now run:
NODE_ENV=production npm start
# For Windows users:
# SET "NODE_ENV=production" && npm start
Congratulations! You now have a production server for this app... 

The server doesn't serve the bundle.js file because at this point we still have not configured the path on the server.js to point to the /public directory.