Add basic example of wac CLI and programatic API

[rylev]

Fixes #51

This adds a simple example showing how wac encode, wac plug, and the wac-graph API work.

[FrankReh]

Would there be any value in the README for this example also saying why wac plug could or could not be used to compose also?

I don't think it's confusing to see what the options are. On the contrary, I'm confused when I think there are other options that aren't mentioned.

[fibonacci1729]

Small fix for the name of the wac document used and optional clarifying question.

Looks great!

[rylev]

I tried to address all the feedback here. Let me know what you think!

[FrankReh]

Wow! Your README is really nice. It very quickly gets to the point and shows three ways of using wac to compose.

I don't think there is any need to provide pros and cons for the various options (which you don't). Anyone reading this will be used to being able to do things in multiple ways and will know that the pros and cons for their situation will become evident when they sit down and start using it.

[FrankReh]

This adds a simple example showing how both wac encode and the wac-graph API work

Maybe tweak this description, since it probably gets into the git log. The example shows how to use wac plug now also.