Move predefined DNS server to rule action

docs/configuration/dns/rule_action.md

@@ -4,7 +4,8 @@ icon: material/new-box
 
 !!! quote "Changes in sing-box 1.12.0"
 
-    :material-plus: [strategy](#strategy)
+    :material-plus: [strategy](#strategy)  
+    :material-plus: [predefined](#predefined)
 
 !!! question "Since sing-box 1.11.0"
 
@@ -31,6 +32,8 @@ Tag of target server.
 
 #### strategy
 
+!!! question "Since sing-box 1.12.0"
+
 Set domain strategy for this query.
 
 One of `prefer_ipv4` `prefer_ipv6` `ipv4_only` `ipv6_only`.
@@ -69,7 +72,7 @@ Will overrides `dns.client_subnet`.
 ```json
 {
   "action": "reject",
-  "method": "default", // default
+  "method": "",
   "no_drop": false
 }
 ```
@@ -81,8 +84,61 @@ Will overrides `dns.client_subnet`.
 - `default`: Reply with NXDOMAIN.
 - `drop`: Drop the request.
 
+`default` will be used by default.
+
 #### no_drop
 
 If not enabled, `method` will be temporarily overwritten to `drop` after 50 triggers in 30s.
 
 Not available when `method` is set to drop.
+
+### predefined
+
+!!! question "Since sing-box 1.12.0"
+
+```json
+{
+  "action": "predefined",
+  "rcode": "",
+  "answer": [],
+  "ns": [],
+  "extra": []
+}
+```
+
+`predefined` responds with predefined DNS records.
+
+#### rcode
+
+The response code.
+
+| Value      | Value in the legacy rcode server | Description     |
+|------------|----------------------------------|-----------------|
+| `NOERROR`  | `success`                        | Ok              |
+| `FORMERR`  | `format_error`                   | Bad request     |
+| `SERVFAIL` | `server_failure`                 | Server failure  |
+| `NXDOMAIN` | `name_error`                     | Not found       |
+| `NOTIMP`   | `not_implemented`                | Not implemented |
+| `REFUSED`  | `refused`                        | Refused         |
+
+`NOERROR` will be used by default.
+
+#### answer
+
+List of text DNS record to respond as answers.
+
+Examples:
+
+| Record Type | Example                       |
+|-------------|-------------------------------|
+| `A`         | `localhost. IN A 127.0.0.1`   |
+| `AAAA`      | `localhost. IN AAAA ::1`      |
+| `TXT`       | `localhost. IN TXT \"Hello\"` |
+
+#### ns
+
+List of text DNS record to respond as name servers.
+
+#### extra
+
+List of text DNS record to respond as extra records.