Add note about run time limitation on login nodes

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

@@ -20,6 +20,7 @@ users and the ZIH.
   - IPs: 141.30.73.82/83
 - Direct access to these nodes is granted via IP whitelisting (contact
   hpcsupport@zih.tu-dresden.de) - otherwise use TU Dresden VPN.
+- Run time limitation: any process will timeout after 5 minutes.
 
 ## AMD Rome CPUs + NVIDIA A100