Added more tips

README.md

@@ -66,3 +66,9 @@ To release files that are blocked, use this command if you want to delete
 ```sh
 zfs list -t snap -o name | grep <dataset> | xargs -n 1 zfs release -r zfs_autobackup:offsite1
 ```
+
+If delete fails after, check other holds on the snapshot
+
+```sh
+zfs holds path@snapshotname
+```