[Resources] generic: add subnet (#285)

diagrams/generic/network.py

@@ -16,6 +16,10 @@ class Router(_Network):
     _icon = "router.png"
 
 
+class Subnet(_Network):
+    _icon = "subnet.png"
+
+
 class Switch(_Network):
     _icon = "switch.png"
 

docs/nodes/generic.md

@@ -26,6 +26,7 @@ Node classes list of generic provider.
 
 - **diagrams.generic.network.Firewall**
 - **diagrams.generic.network.Router**
+- **diagrams.generic.network.Subnet**
 - **diagrams.generic.network.Switch**
 - **diagrams.generic.network.VPN**