DOCSP-45409 -- Add storageClass field to YAML example (#1995) (#1999)

(cherry picked from commit 17a375b)

Author: jvincent-mongodb

source/includes/code-examples/yaml-files/example-sharded-cluster.yaml

@@ -688,6 +688,7 @@ spec:
         # 16GB for "data", 1GB for "journal", 3GB for "logs"
         data:
           storage: "20Gi"
+          storageClass: standard # You must define a storageClass, as the Operator creates a PVC, which will only create an associated PV with a backing storageClass.
         logs:
           storage: "4Gi"
           storageClass: standard