Update README.md

Author: drewbo

examples/README.md

@@ -4,7 +4,7 @@
 
 - [Creating a Neural Network to Find Populated Areas in Tanzania](walkthrough-classification-aws.md): Build a classifier using Keras on AWS
 - [Creating a building classifier in Vietnam using MXNet and SageMaker](walkthrough-classification-mxnet-sagemaker.md): Build a classifier on AWS SageMaker
-- [A building detector with TensorFlow API](walkthrough-tensorflow-object-detection): Use the TensorFlow Object Detection API for detecting buildings in Mexico City.
+- [A building detector with TensorFlow API](walkthrough-tensorflow-object-detection.md): Use the TensorFlow Object Detection API for detecting buildings in Mexico City.
 
 ## Example Nets