Add license attestation report

A license attestation report is a document which contains the information of OSS components used in a specific product. Usually, it identifies following information of each OSS: name, version, copyright notice, licensed under which license and the full license text.

From DT's view, I think that a specific product is represented by the project and its version combination.

This document will then be distributed with the product to fulfill the requirement of software license compliance.

It will be great to be able to download this document from DT directly.