PDF exported can't get opened

[damian-m-g]

Hello there, thanks for this gem.

I've found that the example shown in the README.md isn't working. The PDF can't get opened, it's get seen as "corrupted" by Chrome or Adobe Acrobat Reader. I've inquired into the code and by changing the extension from "example.pdf" to "example.png" it works. You may want to take a look at it.

Cheers.

[damian-m-g]

Hi DerekStride, I've submitted a pull request for this matter, I hope it looks good for you.