[130-all-keys-sample] last changes before comments

doc/examples/kea6/all-keys.json

-// This is not an example configuratiion but a test sample for configuration
-// management tools. This in no way reflect a real configuration.
-// If you need to load this file you have to update the interface name (eth1)
-// and the hook library path (/opt/lib/hooks).
+// WARNING: This example configuration is not meant for production use.
+// The Kea DHCPv6 server will refuse this configuration because it contains
+// mutually exclusive configuration parameters.
+//
+// The primary purpose of the example file is to provide a comprehensive
+// list of parameters supported by Kea DHCPv6 server along with the brief
+// description of each parameter.
 {
   "Dhcp6": {
     "client-classes": [
@@ -130,7 +133,7 @@
     ],
     "interfaces-config": {
       "interfaces": [
-        "eth1"
+        "ethX"
       ],
       "re-detect": true
     },
@@ -178,7 +181,7 @@
     "shared-networks": [
       {
         "client-class": "",
-        "interface": "eth1",
+        "interface": "ethX",
         "interface-id": "",
         "name": "my-secret-network",
         "option-data": [],
@@ -195,7 +198,7 @@
           {
             "client-class": "",
             "id": 1,
-            "interface": "eth1",
+            "interface": "ethX",
             "interface-id": "",
             "option-data": [
               {