chore: add MIT License notice to source files and README

README.md

@@ -2,6 +2,8 @@
 
 Go client library and CLI for the [Mail-in-a-Box](https://mailinabox.email/) admin DNS API.
 
+Licensed under the [MIT License](LICENSE).
+
 ## Library
 
 ```go

cmd/miab/main.go

@@ -1,3 +1,7 @@
+// Copyright (c) 2026 Sławomir Koszewski. All rights reserved.
+// Use of this source code is governed by the MIT License
+// that can be found in the LICENSE file.
+
 package main
 
 import (

dns.go

@@ -1,3 +1,7 @@
+// Copyright (c) 2026 Sławomir Koszewski. All rights reserved.
+// Use of this source code is governed by the MIT License
+// that can be found in the LICENSE file.
+
 package miab
 
 import (

dns_test.go

@@ -1,3 +1,7 @@
+// Copyright (c) 2026 Sławomir Koszewski. All rights reserved.
+// Use of this source code is governed by the MIT License
+// that can be found in the LICENSE file.
+
 package miab
 
 import (