📣 borb release 2.0.20

This release is a small feature release.

• SoundAnnotation can now be added to a PDF, enabling you to add voice-clips, music or other audio to your document
• JavaScriptPushButton makes it easier to add your own JavaScript enabled buttons
• minor improvement to TextRankKeywordExtraction

The majority of the work this sprint went into updating the documentation.
You should check it out. All code-samples in the README are now actually stand-alone code files that can be run.
They are automatically included in the README, rather than duplicated (as before), making it a lot easier to maintain the examples repo.