docs: highlight that enhanced-img only works with local files (#12058)

Author: benmccann

documentation/docs/40-best-practices/07-images.md

@@ -24,9 +24,11 @@ Doing this manually is tedious. There are a variety of techniques you can use, d
 
 ## @sveltejs/enhanced-img
 
-> **WARNING**: The `@sveltejs/enhanced-img` package is experimental. It uses pre-1.0 versioning and may introduce breaking changes with every minor version release.
+`@sveltejs/enhanced-img` is a plugin offered on top of Vite's built-in asset handling. It provides plug and play image processing that serves smaller file formats like `avif` or `webp`, automatically sets the intrinsic `width` and `height` of the image to avoid layout shift, creates images of multiple sizes for various devices, and strips EXIF data for privacy. It will work in any Vite-based project including, but not limited to, SvelteKit projects.
 
-`@sveltejs/enhanced-img` builds on top of Vite's built-in asset handling. It offers plug and play image processing that serves smaller file formats like `avif` or `webp`, automatically sets the intrinsic `width` and `height` of the image to avoid layout shift, creates images of multiple sizes for various devices, and strips EXIF data for privacy. It will work in any Vite-based project including, but not limited to, SvelteKit projects.
+> As a build plugin, `@sveltejs/enhanced-img` can only optimize files located on your machine during the build process. If you have an image located elsewhere (such as a path served from your database, CMS, or backend), please read about [loading images dynamically from a CDN](#loading-images-dynamically-from-a-cdn).
+>
+> **WARNING**: The `@sveltejs/enhanced-img` package is experimental. It uses pre-1.0 versioning and may introduce breaking changes with every minor version release.
 
 ### Setup