cluster: update ceph README
diff --git a/cluster/README b/cluster/README
index 4eeb6b7..39f9190 100644
--- a/cluster/README
+++ b/cluster/README
@@ -34,11 +34,21 @@
 The following storage classes use this cluster:
 
  - `waw-hdd-redundant-1` - erasure coded 2.1
+ - `waw-hdd-redundant-1-object` - erasure coded 2.1 object store
 
 A dashboard is available at https://ceph-waw1.hswaw.net/, to get the admin password run:
 
     kubectl -n ceph-waw1 get secret rook-ceph-dashboard-password -o yaml | grep "password:" | awk '{print $2}' | base64 --decode ; echo
 
+Rados Gateway (S3) is available at https://object.ceph-waw1.hswaw.net/. To create
+an object store user consult rook.io manual (https://rook.io/docs/rook/v0.9/ceph-object-store-user-crd.html)
+User authentication secret is generated in ceph cluster namespace (`ceph-waw1`),
+thus may need to be manually copied into application namespace. (see
+`app/registry/prod.jsonnet` comment)
+
+`tools/rook-s3cmd-config` can be used to generate test configuration file for s3cmd.
+Remember to append `:default-placement` to your region name (ie. `waw-hdd-redundant-1-object:default-placement`)
+
 Known Issues
 ============