Apply suggestions from code review

Co-authored-by: Mashhur <[email protected]>

Author: karenzone

reference/fleet/logstash-output.md

@@ -41,7 +41,7 @@ input {
     ssl_certificate_authorities => ["<ca_path>"]
     ssl_certificate => "<server_cert_path>"
     ssl_key => "<server_cert_key_in_pkcs8>"
-    ssl_client_authentication => 
+    ssl_client_authentication => "required"
   }
 }
 
@@ -52,7 +52,7 @@ output {
     data_stream => "true"
     api_key => "<api_key>" <3>
     data_stream => true
-    ssl => true
+    ssl_enabled => true
     ssl_certificate_authorities => "<elasticsearch_ca_path>"
   }
 }