Add code of conduct
Add code of conduct

All Microsoft open source projects, including this one, are now covered by this code of conduct. Call this out explicitly in the readme.
rainersigwald/msbuild,cdmihai/msbuild,chipitsine/msbuild,chipitsine/msbuild,Microsoft/msbuild,nikson/msbuild,sean-gilliam/msbuild,jeffkl/msbuild,mono/msbuild,AndyGerlicher/msbuild,mono/msbuild,chipitsine/msbuild,cdmihai/msbuild,nikson/msbuild,jeffkl/msbuild,chipitsine/msbuild,jeffkl/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,nikson/msbuild,mono/msbuild,rainersigwald/msbuild,jeffkl/msbuild,Microsoft/msbuild,AndyGerlicher/msbuild,sean-gilliam/msbuild,nikson/msbuild,cdmihai/msbuild,rainersigwald/msbuild,Microsoft/msbuild,cdmihai/msbuild,sean-gilliam/msbuild,rainersigwald/msbuild,mono/msbuild,Microsoft/msbuild,AndyGerlicher/msbuild