Correct references to outdated k8s.gcr.io (#1754)

Replace with `registry.k8s.io`

Issue #, if available:

Description of changes:

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Author: jljaco

docs/content/docs/user-docs/field-export.md

@@ -95,7 +95,7 @@ metadata:
 spec:
   containers:
   - name: field-export-demo-container
-    image: k8s.gcr.io/busybox
+    image: registry.k8s.io/busybox
     command: [ "/bin/sh", "-c", "env" ]
     env:
     - name: USER_DATA_BUCKET_LOCATION
@@ -129,4 +129,4 @@ requesting it. {{% /hint %}}
 
 [spec-reference]: ../../../reference/common/v1alpha1/fieldexport/
 [bucket-spec]: ../../../reference/s3/v1alpha1/fieldexport/bucket/#spec
-[rds-tutorial]: ../../tutorials/rds-example/
+[rds-tutorial]: ../../tutorials/rds-example/