[slf4j-dev] [qos-ch/slf4j] f9c4dc: document DCO requirement

[Ceki Gulcu]

  Branch: refs/heads/master
  Home:   https://github.com/qos-ch/slf4j
  Commit: f9c4dcd1dda3d722aa0535075d3ade8721774e92
      https://github.com/qos-ch/slf4j/commit/f9c4dcd1dda3d722aa0535075d3ade8721774e92
  Author: Ceki Gulcu <ceki at qos.ch>
  Date:   2021-07-02 (Fri, 02 Jul 2021)

  Changed paths:
    M README.md

  Log Message:
  -----------
  document DCO requirement