Extend to general purpose plays

[raunofreiberg]

I started using the definition "play" instead of "component" with the intention of possibly not only covering UI components but primitives (techniques? I really can't think of a suitable noun here) such as animation, typography, colors, spacing.

I think there's a lot of valuable information to gather from various folks and sources and merge them into nicely organized plays as follows:

• ~~Animation (distinguish separate tiers of animation: transitions, entry-exit animations, complex coordinated animations etc)~~ live at https://uiplaybook.dev/play/motion!
• Typography (mention capsize?)
• Colors (provide guidelines on how to create a harmonic palette from a single primary color)
• Spacing (emphasize the usage of modular scales for spacing, instead of raw values)