Clarify what is implemented wrt Ceph support

This patch makes minor additions to the Ceph design doc documentation
to clarify that only some parts of the design have been implemented.
Signed-off-by: Hrvoje Ribicic <riba@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>

doc/design-ceph-ganeti-support.rst

@@ -11,9 +11,9 @@ The project aims to improve Ceph RBD support in Ganeti. It can be
 primarily divided into following tasks.
 
 - Use Qemu/KVM RBD driver to provide instances with direct RBD
-  support.
-- Allow Ceph RBDs' configuration through Ganeti.
-- Write a data collector to monitor Ceph nodes.
+  support. [implemented as of Ganeti 2.10]
+- Allow Ceph RBDs' configuration through Ganeti. [unimplemented]
+- Write a data collector to monitor Ceph nodes. [unimplemented]
 
 Background
 ==========