Update lease4-del.json

doc/api/lease4-del.json

@@ -2,7 +2,7 @@
     "name": "lease4-del",
     "brief": "lease4-del can be used to delete a lease from the lease database.",
     "description": "See <xref linkend=\"command-lease4-del\"/>",
-    "support": [ "kea-dhcp4", "kea-dhcp6" ],
+    "support": [ "kea-dhcp4"],
     "avail": "1.3.0",
     "hook": "lease_cmds",
     "cmd-syntax": "{
@@ -11,5 +11,5 @@
         \"ip-address\": \"192.0.2.202\"
     }
 }",
-    "cmd-comment": "leaseX-del returns a result that indicates a outcome of the operation. It has one of the following values: 0 (success), 1 (error) or 3 (empty). The empty result means that a query has been completed properly, but the object (a lease in this case) has not been found."
-}
+    "cmd-comment": "Specify the lease to be deleted either by IP address, or by identifier-type and identifier value. Currently supported identifiers are \"hw-address\" and \"client-id\"."
+}
\ No newline at end of file