Add simple description for image preview extension

Fixes #81741

extensions/image-preview/README.md

 # Image Preview
 
 **Notice:** This extension is bundled with Visual Studio Code. It can be disabled but not uninstalled.
+
+## Features
+
+This extension provides VS Code's built-in image preview functionality.
+
+Supported image formats:
+
+- `*.jpg`, `*.jpe`, `*.jpeg`
+- `*.png`
+- `*.bmp`
+- `*.gif`
+- `*.ico`
+- `*.tga`
+- `*.tif`, `*.tiff`
+- `*.webp`

extensions/image-preview/package.nls.json

 {
 	"displayName": "Image Preview",
-	"description": "Previews images.",
+	"description": "Provides VS Code's built-in image preview",
 	"webviewEditors.displayName": "Image Preview"
 }