fix: upload docs

Author: AllanZhengYP

src/pages/[platform]/build-a-backend/storage/upload-files/index.mdx

@@ -653,7 +653,6 @@ Option | Type | Description |
 | -- | -- | ----------- |
 | getProperties | boolean | Whether to retrieve properties for the uploaded object using theAmplify.Storage.getProperties() after the operation completes. When set to true the returned item will contain additional info such as metadata and content type. |
 | useAccelerateEndpoint | boolean | Whether to use accelerate endpoint. <br/><br/> Read more at [Transfer Acceleration](/[platform]/build-a-backend/storage/upload-files/#transfer-acceleration) |
-| expectedBucketOwner | string | Optional | The account ID that owns requested bucket. |
 
 Example of `uploadFile` with options:
 
@@ -1579,6 +1578,8 @@ Option | Type | Default | Description |
 | contentDisposition | string | — | Specifies presentational information for the object. <br/><br/> Read more at [Content-Disposition documentation](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition) |
 | metadata | map\<string\> | — | A map of metadata to store with the object in S3. <br/><br/> Read more at [S3 metadata documentation](https://docs.aws.amazon.com/AmazonS3/latest/userguide/UsingMetadata.html#UserMetadata) |
 | useAccelerateEndpoint | boolean | false | Whether to use accelerate endpoint. <br/><br/> Read more at [Transfer Acceleration](/[platform]/build-a-backend/storage/upload-files/#transfer-acceleration) |
+| expectedBucketOwner | string | - | The account ID that owns requested bucket. |
+| preventOverwrite | boolean | false | If set, the library checks if an object with the same key already exists before completing the upload. If exists, a `Precondition Failed` error will be thrown |
 
 <Callout>