[DLMED] init the tutorial

Signed-off-by: Nic Ma <[email protected]>

Author: Nic-Ma

model_zoo/readme.md renamed to model_zoo/README.md

@@ -1,3 +1,5 @@
+This folder contains typical usage examples of the bundles in MONAI model-zoo.
+
 ## Getting Started
 
 To download and get started with the models, please see also https://monai.io/model-zoo.

model_zoo/extend_workflow_with_handler/README.md

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+# Overview
+This tutorial shows how to extend the features of workflow in the model-zoo bundles based on `event-handler` mechanism.
+
+## Event-handler mechanism
+placeholder
+
+## Download example monai bundle from model-zoo
+```
+python -m monai.bundle download --name spleen_ct_segmentation --version "0.1.1" --bundle_dir "./"
+```
+
+## Extend the workflow to print the execution time for every iteration, every epoch and total time
+placeholder
+
+## Commands example
+To run the workflow with customized components, `PYTHONPATH` should be revised to include the path to the customized component:
+```
+export PYTHONPATH=$PYTHONPATH:"<path to 'spleen_ct_segmentation/scripts'>"
+```
+And please make sure the folder `spleen_ct_segmentation/scripts` is a valid python module (it has a `__init__.py` file in the folder).
+
+Execute training:
+
+```
+python -m monai.bundle run training --meta_file configs/metadata.json --config_file configs/train.json --logging_file configs/logging.conf
+```