fix: update lego.

vendor/github.com/Azure/go-autorest/autorest/to/convert.go

@@ -3,6 +3,20 @@ Package to provides helpers to ease working with pointer values of marshalled st
 */
 package to
 
+// Copyright 2017 Microsoft Corporation
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+
 // String returns a string value for the passed string pointer. It returns the empty string if the
 // pointer is nil.
 func String(s *string) string {