[Images] Update quality.mdx (#20948)

Can we inform about `format=auto`  here as well?

From https://developers.cloudflare.com/images/polish/compression/#polish-interaction-with-image-optimization

Author: nenizera

src/content/partials/images/quality.mdx

@@ -7,7 +7,7 @@ import { Tabs, TabItem } from "~/components"
 At the moment, this setting only works directly with [image transformations](/images/transform-images/).
 :::
 
-Specifies quality for images in JPEG, WebP, and AVIF formats. The quality is in a 1-100 scale, but useful values are between `50` (low quality, small file size) and `90` (high quality, large file size). `85` is the default. When using the PNG format, an explicit quality setting allows use of PNG8 (palette) variant of the format.
+Specifies quality for images in JPEG, WebP, and AVIF formats. The quality is in a 1-100 scale, but useful values are between `50` (low quality, small file size) and `90` (high quality, large file size). `85` is the default. When using the PNG format, an explicit quality setting allows use of PNG8 (palette) variant of the format. Use the `format=auto` option to allow use of WebP and AVIF formats.
 
 We also allow setting one of the perceptual quality levels `high|medium-high|medium-low|low`