Make difference between attribute and property clearer

[tricki]

I keep seeing people using attributes in JSX and wondering why they can't pass objects to child components (for example in this issue and more recently in this StackOverflow question).

The docs are somewhat vague about the difference:

In the JavaScript ecosystem, it's common to use 'camelCase' when naming variables.

and:

When we use our component in a TSX file, an attribute uses camelCase

(which is incorrect since camelCase refers to the property instead)

Some information about how Stencil parses and transforms attributes in general (e.g. parsing strings to booleans and numbers) would also be great, but that might be outside the scope of this request.

Maybe add a link to https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes#content_versus_idl_attributes