Clarify diskless and diskfull nodes within Barnard

doc.zih.tu-dresden.de/docs/jobs_and_resources/hardware_overview.md

@@ -135,10 +135,11 @@ required):
 The cluster `Barnard` is a general purpose cluster by Bull. It is based on Intel Sapphire Rapids
 CPUs.
 
-- 630 diskless nodes, each with
+- 630 nodes, each with
     - 2 x Intel Xeon Platinum 8470 (52 cores) @ 2.00 GHz, Multithreading enabled
     - 512 GB RAM
     - 12 nodes provide 1.8 TB local storage on NVMe device at `/tmp`
+    - All other nodes are diskless and have no or very limited local storage (i.e. `/tmp`)
 - Login nodes: `login[1-4].barnard.hpc.tu-dresden.de`
 - Hostnames: `n[1001-1630].barnard.hpc.tu-dresden.de`
 - Operating system: Red Hat Enterpise Linux 8.7