chore: add notice

Author: mrjoelkamp

NOTICE

@@ -0,0 +1,15 @@
+Docker attest
+Copyright 2024 Docker attest authors
+
+This product includes software developed at Docker, Inc. (https://www.docker.com).
+
+The following is courtesy of our legal counsel:
+
+Use and transfer of Docker may be subject to certain restrictions by the
+United States and other governments.
+It is your responsibility to ensure that your use and/or transfer does not
+violate applicable laws.
+
+For more information, please see https://www.bis.doc.gov
+
+See also https://www.apache.org/dev/crypto.html and/or seek legal counsel.