Fix CA in authentication example

Author: enj

content/en/blog/_posts/2024-04-25-structured-authentication-configuration-beta.md

@@ -172,7 +172,7 @@ jwt:
     url: https://issuer.example.com
     audiences:
     - example-client-id
-  certificateAuthority: <value is the content of file /path/to/ca.pem>
+    certificateAuthority: <value is the content of file /path/to/ca.pem>
   claimMappings:
     username:
       claim: username