Missing copyright notice

[Exagone313]

Hi,

I noticed the project doesn't have a copyright notice. It only contains the Apache 2.0 license.

You can read the appendix at the end of the license to understand how to add a proper copyright notice.

At the very least, include your name and the year of the first licensed commit (2017). You can also add a line for json-logging contributors.

The copyright notice can be added to the NOTICE file (read the license text which mentions the use of this file). This file can be included in every distribution (including package distribution),