docs: add preload example for NuxtImg (#2124)

Co-authored-by: Daniel Roe <daniel@roe.dev>

Author: divagueame

docs/content/2.usage/1.nuxt-img.md

@@ -368,6 +368,14 @@ In case you want to preload the image, use this prop. This will place a correspo
 <NuxtImg src="/nuxt-icon.png" preload />
 ```
 
+Passing an object to the preload prop lets you define the `fetchPriority` property.
+Note that the JavaScript property `fetchPriority` maps to the [`fetchpriority`](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Attributes/fetchpriority) HTML attribute in the preload link tag.
+Accepted values are `auto`, `high`, or `low`.
+
+```vue
+<NuxtImg src="/nuxt-icon.png" :preload="{ fetchPriority: 'high' }" />
+```
+
 ### `loading`
 
 This is a [native](https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement/loading) attribute that provides a hint