Need to describe stream's chunk type more clearly

[yutakahirano]

Asked by @wanderview at #25.

I think it would be better to define the Uint8Array chunk type where you define the stream concept for the object. Placing the chunk type down in ConsumeStream, etc makes it a bit hard to find.
Can you expand on what you means here?

[wanderview]

I mean change the text like this:

A Response object has an associated readable stream (initially an empty ReadableByteStream).

To something like:

A Response object has an associated readable stream (initially an empty ReadableByteStream). This stream must produce chunks of type Uint8Array.

[yutakahirano]

Fixed. fe6e740