JShell tool tutorial

[Robert Field]

I'm working on a better web location, but here is the tutorial I've been 
working on:

     http://cr.openjdk.java.net/~rfield/tutorial/JShellTutorial.html

It is still a work-in-progress, but it still has a lot of information 
that isn't available anywhere else.

I'd love feedback, at any granularity, from subjects that should be 
added to grammar/spelling.

Enjoy,
Robert