docs(assets): update static asset URL transformation in dev (#18842)

Author: onildof

docs/guide/assets.md

@@ -14,7 +14,7 @@ import imgUrl from './img.png'
 document.getElementById('hero-img').src = imgUrl
 ```
 
-For example, `imgUrl` will be `/img.png` during development, and become `/assets/img.2d8efhg.png` in the production build.
+For example, `imgUrl` will be `/src/img.png` during development, and become `/assets/img.2d8efhg.png` in the production build.
 
 The behavior is similar to webpack's `file-loader`. The difference is that the import can be either using absolute public paths (based on project root during dev) or relative paths.