Create code-of-conduct.md (#54)
Create code-of-conduct.md (#54)

* Create code-of-conduct.md

* Add header for Jekyll
scikit-hep/scikit-hep.github.io,scikit-hep/scikit-hep.github.io,scikit-hep/scikit-hep.github.io,scikit-hep/scikit-hep.github.io