The "ref" issue

[embiem]

There have been some questions regarding how to use references with react-canvas-draw. I'll pull the issues #107 #106 & #104 into this one.

• Make sure we understand what ppl wanna do with a reference
• Add proper example to the docs/README (example: How to use references????  #104 (comment))

[vmz-tim]

The actual canvas element is for whatever reason: canvas.current.canvasContainer.children[1]

I don´t get why its not just in the docs.