Source release tarball does not match repository in 3.6.0

During the release of 3.6.0, rc0, I noticed that the source tarball differs from the repository:

• there is no "dev/docker" directory (so we are missing a part of the codebase, even this is not so important)
• there is no "zookeeper-metrics-providers" directory (so the project is not buildable)
• the c client directory contains temporary files (so we are including 'binaries')

I have also noted that NOTICE file report 2019 and it should be 2020