chore: Updates examples link in index.md for v1.21.4 release

docs/index.md

@@ -220,7 +220,7 @@ We ship binaries but do not prioritize fixes for the following operating system
 ## Examples from MongoDB and the Community
 
 <!-- NOTE: the below examples link is updated during the release process, when doing changes in the following sentence verify scripts/update-examples-reference-in-docs.sh is not impacted-->
-We have [example configurations](https://github.com/mongodb/terraform-provider-mongodbatlas/tree/v1.21.3/examples)
+We have [example configurations](https://github.com/mongodb/terraform-provider-mongodbatlas/tree/v1.21.4/examples)
 in our GitHub repo that will help both beginner and more advanced users.
 
 Have a good example you've created and want to share?