fix: fix path to train target in hello_world example (#2608)

BUG=cleanup

tensorflow/lite/micro/examples/hello_world/quantization/ptq.py

diff --git a/tensorflow/lite/micro/examples/hello_world/quantization/ptq.py b/tensorflow/lite/micro/examples/hello_world/quantization/ptq.py
index bfab0d0..f1c4210 100644
--- a/tensorflow/lite/micro/examples/hello_world/quantization/ptq.py
+++ b/tensorflow/lite/micro/examples/hello_world/quantization/ptq.py
@@ -16,7 +16,7 @@
 
 Run:
 Build the train.py script
-`bazel build tensorflow/lite/micro/examples/hello_world/quantization:train`
+`bazel build tensorflow/lite/micro/examples/hello_world:train`
 
 The following command first creates the trained TF float model that we will quantize later
 `bazel-bin/tensorflow/lite/micro/examples/hello_world/train --save_tf_model --save_dir=/tmp/float_model/`
@@ -113,4 +113,4 @@
 
 
 if __name__ == "__main__":
-  app.run(main)
\ No newline at end of file
+  app.run(main)