Update nginx.md
Update nginx.md

Fixed security warning, changed to "anyone who can log on to the server where your Docker Registry is running"
londoncalling/docker.github.io,londoncalling/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,docker/docker.github.io,thaJeztah/docker.github.io,londoncalling/docker.github.io,londoncalling/docker.github.io,thaJeztah/docker.github.io,londoncalling/docker.github.io