Be a bit more berbose in variable names.
Preferring actual words "request" and "response" instead of
abbreviations "req" and "res".
Add Hello World node app
This is similar to what is documented here:
https://medium.com/@adnanrahic/hello-world-app-with-node-js-and-express-
c1eb7cfa8a30
but with some more modern content as recommended by Richard.
This can be run with:
node server
in the current directory, (and then pointing a user agent at localhost:3000).