Vague documentation

[greena13]

Hey, thanks for the great package. I have been looking around for something that will allow me to easily define keyboard shortcuts in React apps for a while.

Unfortunately, the documentation could be improved:

• The installation instructions are concise and informative, but the documentation of how to use <Shortcuts> is not very clear, imho
• The event propagation behaviour is unclear when multiple <Shortcuts> are used - especially when nested
• The default behaviour as it relates to stopPropagation and isolate is unclear
• None of the behaviour documented through the test suite is summarised on the project's readme
• There is no troubleshooting information

I've taken notes while I've been using the package, read through the test suite and done some experiments so I am going to create a pull request that I am hoping will improve the points above.