Add new file

doc/api/lease4-del.json

+{
+    "name": "lease4-del",
+    "brief": "lease4-del can be used to delete a lease from the lease database.",
+    "description": "See <xref linkend=\"lease4-del\"/>",
+    "support": [ "kea-dhcp4", "kea-dhcp6" ],
+    "avail": "1.3.0",
+    "hook": "lease_cmds",
+    "cmd-syntax": "{
+    \"command\": \"lease4-del\",
+    \"arguments\": {
+        \"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.",
+}
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