documentation: Add rule action

docs/configuration/dns/rule_action.md

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+---
+icon: material/new-box
+---
+
+# DNS Rule Action
+
+!!! question "Since sing-box 1.11.0"
+
+### route
+
+```json
+{
+  "action": "route",  // default
+  "server": "",
+  
+  // for compatibility
+  "disable_cache": false,
+  "rewrite_ttl": 0,
+  "client_subnet": null
+}
+```
+
+`route` inherits the classic rule behavior of routing DNS requests to the specified server.
+
+#### server
+
+==Required==
+
+Tag of target server.
+
+#### disable_cache/rewrite_ttl/client_subnet
+
+!!! failure "Deprecated in sing-box 1.11.0"
+
+    Legacy route options is deprecated and will be removed in sing-box 1.12.0, check [Migration](/migration/#migrate-legacy-dns-route-options-to-rule-actions).
+
+### route-options
+
+```json
+{
+  "action": "route-options",
+  "disable_cache": false,
+  "rewrite_ttl": null,
+  "client_subnet": null
+}
+```
+
+#### disable_cache
+
+Disable cache and save cache in this query.
+
+#### rewrite_ttl
+
+Rewrite TTL in DNS responses.
+
+#### client_subnet
+
+Append a `edns0-subnet` OPT extra record with the specified IP prefix to every query by default.
+
+If value is an IP address instead of prefix, `/32` or `/128` will be appended automatically.
+
+Will overrides `dns.client_subnet` and `servers.[].client_subnet`.
+
+### reject
+
+```json
+{
+  "action": "reject",
+  "method": "default", // default
+  "no_drop": false
+}
+```
+
+`reject` reject DNS requests.
+
+#### method
+
+- `default`: Reply with NXDOMAIN.
+- `drop`: Drop the request.
+
+#### 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.