fix format in external-storage-uri.md (#17862)

external-storage-uri.md

@@ -26,7 +26,7 @@ The basic format of the URI is as follows:
     - `endpoint`: Specifies the URL of custom endpoint for S3-compatible services (for example, `<https://s3.example.com/>`).
     - `force-path-style`: Use path style access rather than virtual hosted style access (defaults to `true`).
     - `storage-class`: Specifies the storage class of the uploaded objects (for example, `STANDARD` or `STANDARD_IA`).
-    - `sse`: Specifies the server-side encryption algorithm used to encrypt the uploaded objects (value options: ``, `AES256`, or `aws:kms`).
+    - `sse`: Specifies the server-side encryption algorithm used to encrypt the uploaded objects (value options: empty, `AES256`, or `aws:kms`).
     - `sse-kms-key-id`: Specifies the KMS ID if `sse` is set to `aws:kms`.
     - `acl`: Specifies the canned ACL of the uploaded objects (for example, `private` or `authenticated-read`).
     - `role-arn`: When you need to access Amazon S3 data from a third party using a specified [IAM role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html), you can specify the corresponding [Amazon Resource Name (ARN)](https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) of the IAM role with the `role-arn` URL query parameter, such as `arn:aws:iam::888888888888:role/my-role`. For more information about using an IAM role to access Amazon S3 data from a third party, see [AWS documentation](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_common-scenarios_third-party.html). BR supports this parameter starting from v7.6.0.