Updated URL for developing plugins (#25521)

The existing link for developing plugins was redirecting to the legacy plugin docs page for developers. I updated it to the new link for latest post-7.0 release. 👍

CONTRIBUTING.md

@@ -64,4 +64,4 @@ Before we can accept your pull request, you need to [sign our CLA](https://grafa
 
 
 - Set up your [development environment](contribute/developer-guide.md).
 - Set up your [development environment](contribute/developer-guide.md).
 - Learn how to [contribute documentation](contribute/documentation.md).
 - Learn how to [contribute documentation](contribute/documentation.md).
-- Get started [developing plugins](https://grafana.com/docs/plugins/developing/development/) for Grafana.
+- Get started [developing plugins](https://grafana.com/docs/grafana/latest/developers/plugins/) for Grafana.