Update link for customArray (rjsf-team#1702)

It seems RJSF has been split out of mozilla to a separate repo, i found this link to be out of date. Co-authored-by: Ashwin Ramaswami <aramaswamis@gmail.com>

Author: ml242

docs/advanced-customization.md

@@ -108,7 +108,7 @@ render((
 ), document.getElementById("app"));
 ```
 
-Please see [customArray.js](https://github.com/mozilla-services/react-jsonschema-form/blob/master/playground/samples/customArray.js) for a better example.
+Please see [customArray.js](https://github.com/rjsf-team/react-jsonschema-form/blob/master/packages/playground/src/samples/customArray.js) for a better example.
 
 
 The following props are passed to each `ArrayFieldTemplate`: