Remove the code of conduct

[Garanas]

Description of the proposed changes

Removes the code of conduct. The code of conduct is still provided, but instead originates from one location:

• FAForever/.github

This is a feature of Github. It is not particularly well documented by Github however. See also:

• https://www.freecodecamp.org/news/how-to-use-the-dot-github-repository/
• https://github.com/joelparkerhenderson/github-special-files-and-paths

Testing done on the proposed changes

Review other repositories that have no code of conduct in the repository and GitHub links to the code of conduct in the .github location, as an example:

• https://github.com/FAForever/FA-Binary-Patches