config-linux: add example of cgroup resource limits

The example section looks very sparse otherwise.

Signed-off-by: Aleksa Sarai <asarai@suse.de>

Author: cyphar

config-linux.md

@@ -182,6 +182,18 @@ However, a runtime CAN decide to not attach to any additional cgroup controllers
 
 ```json
    "cgroupsPath": "/myRuntime/myContainer"
+   "resources": {
+      "memory": {
+         "limit": 100000,
+         "reservation": 200000
+      },
+      "devices": [
+         {
+            "allow": false,
+            "access": "rwm"
+         }
+      ]
+   }
 ```
 
 #### Device whitelist