[5241] Added syntax, doc, parser, etc, but not the function

doc/examples/kea6/multiple-options.json

@@ -111,6 +111,15 @@
             {
                 "name": "bootfile-param",
                 "data": "root=/dev/sda2, quiet, splash"
+            },
+
+            // At a few exceptions options are added to response only when
+            // the client requests them. The persistent flag should be used
+            // to enforce a particular option.
+            {
+                "name": "pana-agent",
+                "data": "2001:db8:2::123",
+                "persistent": true
             }
       ],
       "pools": [