LinuxKit applies the [Docker code of conduct](https://github.com/docker/code-of-conduct).

For further information, see also the [contributing guide](CONTRIBUTING.md) and the [maintainers file](MAINTAINERS).

Add code of conduct link to Github recommended location
Add code of conduct link to Github recommended location

See recommendations at https://help.github.com/articles/adding-a-code-of-conduct-to-your-project/

Signed-off-by: Justin Cormack <af64ee19f04db9509cb02b0e470e11e5402ef9b3@docker.com>
