Add WASI P3 examples

WASI P3 is almost here! We should add some WASI P3 examples. For example, we could add a streamed response example. I am not sure where this would fit in the structure of the component book right now. @itowlson do you have any ideas here? Maybe a tutorial?

Start by reading the existing component book structure to determine where WASI P3 examples belong. Focus on adding examples such as a streamed response example, and consider whether a tutorial is the right format; done means the examples are included in a documented, agreed location.

索引モデルが issue の本文から書いたものです。