Clarify docs on kebab-case vs camelCase

[christopherjbaker]

Clarify docs on kebab-case vs camelCase, and add code to detect camelCase usage in dev mode.

[sven-from-sylphen]

Maybe extending the Working With Attributes-Example in the ReadMe to a use-case where it additionally uses a property that gets changed to kebab-case could be helpful as well, as that was the first place I looked to find out what my issue could be.