docs: page for reactivity & attributy naming

[MentalGear]

Is your feature request or improvement related to a problem?

There is no search function in the docs, I searched manually for reactivity, and ended up with an older blog post after a while, which also mentioned reactivity on arrays, but didn't mention objects or never js constructs like maps.

Solution you'd like

It would be great to have a page dedicated to reactivity, how it works, possible gotchas and a table with which js constructs it works out of the box.

Alternatives you've considered

Searching the docs, very tiresome since also no search function.

Additional context

One of the most important things when checking out a new framework is understanding the workings & ergonomics of reactivity.

[tipiirai]

Good points. Currently working on how to implement single-page applications, after which the concept of reactivity is much more broadly documented. ETA: 1.3