Add Docker `--file` argument to build (#7527)

utils/docker/Dockerfile

@@ -32,7 +32,7 @@ ENV OMP_NUM_THREADS=8
 # Usage Examples -------------------------------------------------------------------------------------------------------
 
 # Build and Push
-# t=ultralytics/yolov5:latest && sudo docker build -t $t . && sudo docker push $t
+# t=ultralytics/yolov5:latest && sudo docker build -f utils/docker/Dockerfile -t $t . && sudo docker push $t
 
 # Pull and Run
 # t=ultralytics/yolov5:latest && sudo docker pull $t && sudo docker run -it --ipc=host --gpus all $t

utils/docker/Dockerfile-cpu

@@ -31,7 +31,7 @@ ADD https://ultralytics.com/assets/Arial.ttf https://ultralytics.com/assets/Aria
 # Usage Examples -------------------------------------------------------------------------------------------------------
 
 # Build and Push
-# t=ultralytics/yolov5:latest-cpu && sudo docker build -t $t . && sudo docker push $t
+# t=ultralytics/yolov5:latest-cpu && sudo docker build -f utils/docker/Dockerfile-cpu -t $t . && sudo docker push $t
 
 # Pull and Run
 # t=ultralytics/yolov5:latest-cpu && sudo docker pull $t && sudo docker run -it --ipc=host -v "$(pwd)"/datasets:/usr/src/datasets $t