Revert "Fix command line to start nodejs process"

This reverts commit 90d6a64bdcb5845b83d4c3f4003b6de62c905fbb.

In this tutorial environment, Ubuntu, Node.js is installed as
`nodejs` command.
Fix command name for Node.js

Replace `node` with `nodejs`.
In this tutorial environment, Node.js is installed as
`nodejs` command.