Documentation fix for package 'health'. Use proper import path for 'health/api'
// "manual" checks that allow the service to quickly be brought in/out of
// rotation.
//
-// import _ "github.com/docker/distribution/registry/health/api"
+// import _ "github.com/docker/distribution/health/api"
//
// # curl localhost:5001/debug/health
// {}
