Document the output of text-to-image model bindings

[TheGeorgeAlexander]

Existing documentation URL(s)

• https://developers.cloudflare.com/workers-ai/models/stable-diffusion-xl-lightning/#Output
• https://developers.cloudflare.com/workers-ai/models/dreamshaper-8-lcm/#Output
• https://developers.cloudflare.com/workers-ai/models/stable-diffusion-v1-5-img2img/#Output
• https://developers.cloudflare.com/workers-ai/models/stable-diffusion-v1-5-inpainting/#Output
• https://developers.cloudflare.com/workers-ai/models/stable-diffusion-xl-base-1.0/#Output

What changes are you suggesting?

For all these pages, the Output section is empty. The object returned by the binding is not documented.

Show that the output from the binding is a ReadableStream. Not a buffer, JSON object or anything else the developer may guess. A simple sentence may be:

## Output

The binding returns a `ReadableStream` with the image in PNG format.

Additional information

No response