Replace deprecated usage of ioutil in sample code (#6872)

sfc-gh-kleonhard · web-flow · commit d14ee26877ef · 2022-10-19T00:04:12.000-04:00
diff --git a/storage/README.md b/storage/README.md
@@ -25,7 +25,7 @@ if err != nil {
 	log.Fatal(err)
 }
 defer rc.Close()
-body, err := ioutil.ReadAll(rc)
+body, err := io.ReadAll(rc)
 if err != nil {
 	log.Fatal(err)
 }
