[Documentation] More examples?

[rubyFeedback]

I went through the default examples such as:

png[1,1] = ChunkyPNG::Color.rgba(10, 20, 30, 128)

Would it be possible to add more examples what one can do via chunky png?

I like to work on a tutorial-like way based on examples. That way I can modify
the code and learn as I go. This has been very effective for me in learning new
libraries. I also would like to compare chunky png with imagemagick, just to
know which effects may be useful.

Perhaps an examples/ directory could be added? or examples/ or samples/
or sample/