documentation: Fix Rcode's migration guide

Signed-off-by: Sentsuki <52487960+Sentsuki@users.noreply.github.com>

cmd/internal/build_libbox/main.go

@@ -112,6 +112,8 @@ func buildAndroid() {
 		args = append(args, debugFlags...)
 	}
 
+	args = append(args, "-ldflags", "-checklinkname=0")
+
 	tags := append(sharedTags, memcTags...)
 	if debugEnabled {
 		tags = append(tags, debugTags...)

docs/migration.md

@@ -351,14 +351,15 @@ DNS servers are refactored for better performance and scalability.
         ```json
         {
           "dns": {
-            "servers": [
+            "rules": [
               {
-                "type": "predefined",
-                "responses": [
-                  {
-                    "rcode": "REFUSED"
-                  }
-                ]
+                "domain": [
+                  "example.com"
+                ],
+                // other rules
+                
+                "action": "predefined",
+                "rcode": "REFUSED"
               }
             ]
           }

docs/migration.zh.md

@@ -351,14 +351,15 @@ DNS 服务器已经重构。
         ```json
         {
           "dns": {
-            "servers": [
+            "rules": [
               {
-                "type": "predefined",
-                "responses": [
-                  {
-                    "rcode": "REFUSED"
-                  }
-                ]
+                "domain": [
+                  "example.com"
+                ],
+                // 其它规则
+                
+                "action": "predefined",
+                "rcode": "REFUSED"
               }
             ]
           }

experimental/libbox/pidfd_android.go

@@ -0,0 +1,19 @@
+package libbox
+
+import (
+	"os"
+	_ "unsafe"
+)
+
+// https://github.com/SagerNet/sing-box/issues/3233
+// https://github.com/golang/go/issues/70508
+// https://github.com/tailscale/tailscale/issues/13452
+
+//go:linkname checkPidfdOnce os.checkPidfdOnce
+var checkPidfdOnce func() error
+
+func init() {
+	checkPidfdOnce = func() error {
+		return os.ErrInvalid
+	}
+}