incorrect env var..

Author: lerouxb

.evergreen/setup-env.sh

@@ -75,7 +75,7 @@ if [ "$OS" == "Windows_NT" ]; then
   export npm_config_logs_dir="$(cygpath -w "$npm_config_logs_dir")"
 fi
 
-export DOCKER_FILE="$BASEDIR/docker-config/config.json"
+export DOCKER_CONFIG="$BASEDIR/docker-config/config.json"
 export PATH="BASEDIR/docker-config/bin:$PATH"
 
 echo "Running on:"