docs: Add missing , (#1936)

Will remove the syntax error when copying the code

---------

Co-authored-by: Christian Georgi <[email protected]>

Author: tklein1801

node.js/cds-log.md

@@ -245,7 +245,7 @@ You can specify winston custom options to that method [as documented for `winsto
 
 ```js
 cds.log.Logger = cds.log.winstonLogger({
-  format: winston.format.simple()
+  format: winston.format.simple(),
   transports: [
     new winston.transports.Console(),
     new winston.transports.File({