Update of code of conduct

[lucian-balea]

• Do you want to request a feature or report a bug?

bug

• What is the current behavior?

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

• What is the expected behavior?

LFE has approved of new code of conduct.
Please update reference to CoC in CONTRIBUTING:

New reference:
This project applies the [LF Energy Code of Conduct](https://www.lfenergy.org/about/code-of-conduct/). By participating, you are expected to uphold this code. Please report unacceptable behavior to the project's Technical Steering Committee [[email protected]](mailto:[email protected]).

ALso remove existing CODE_OF_CONDUCT file

• What is the motivation / use case for changing the behavior?

• Please tell us about your environment:

  • PowSyBl Version: ...
  • OS Version: ...

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. stackoverflow, spectrum, etc)

(if a question doesn't apply, you can delete it)

[mathbagu]

This as been taken into account in the new version of the website