v3 docs on arrays and missing Map and Set docs plus good examples

[AddictArts]

Some feedback from a first time user, but experienced React state user, what I ran into right away.

While this mentions arrays ....

https://legendapp.com/open-source/state/v3/usage/observable/#arrays

the examples, especially with React are nearly non existed or really not enough. I found it somewhat difficult to follow anything in the state / store that was more than a string or number. There were many of those examples; However, Map and Set seemed non existent. Hopefully they are covered and or on the roadmap. Maybe this is addressed, apologies if I missed it.

PS: If it matters to you, the site legendapp.com/open-source/state is awful page loads and transitions between navigation in Firefox and more importantly Zen.