Edit the MediaUpload documentation about Upload Permissions

Include some informations about how to make sure the current user has upload permissions (by wrapping the MediaUpload component into the MediaUploadCheck one)

packages/editor/src/components/media-upload/README.md

@@ -24,25 +24,28 @@ You can check how this component is implemented for the edit post page using `wp
 
 ## Usage
 
+To make sure the current user has Upload permissions, you need to wrap the MediaUpload component into the MediaUploadCheck one.
 
 ```jsx
 import { Button } from '@wordpress/components';
-import { MediaUpload } from '@wordpress/editor';
+import { MediaUpload, MediaUploadCheck } from '@wordpress/editor';
 
 const ALLOWED_MEDIA_TYPES = [ 'audio' ];
 
 function MyMediaUploader() {
 	return (
-		<MediaUpload
-			onSelect={ ( media ) => console.log( 'selected ' + media.length ) }
-			allowedTypes={ ALLOWED_MEDIA_TYPES }
-			value={ mediaId }
-			render={ ( { open } ) => (
-				<Button onClick={ open }>
-					Open Media Library
-				</Button>
-			) }
-		/>
+		<MediaUploadCheck>
+			<MediaUpload
+				onSelect={ ( media ) => console.log( 'selected ' + media.length ) }
+				allowedTypes={ ALLOWED_MEDIA_TYPES }
+				value={ mediaId }
+				render={ ( { open } ) => (
+					<Button onClick={ open }>
+						Open Media Library
+					</Button>
+				) }
+			/>
+		</MediaUploadCheck>
 	);
 }
 ```