Add: - awesome README based on [this guide](https://github.com/src-d/guide/blob/master/engineering/documentation.md), and [fill placeholders](https://github.com/src-d/code-annotation/pull/12#pullrequestreview-89816444) - [DCO](https://github.com/src-d/guide/blob/master/engineering/licensing.md#developer-certificate-of-origin) - DCO sign-off-checker -
