Merge pull request tensorflow#1567 from tensorflow/readme

Add object_detection to the main README

README.md

@@ -27,6 +27,7 @@ running TensorFlow 0.12 or earlier, please
 - [neural_gpu](neural_gpu): highly parallel neural computer.
 - [neural_programmer](neural_programmer): neural network augmented with logic and mathematic operations.
 - [next_frame_prediction](next_frame_prediction): probabilistic future frame synthesis via cross convolutional networks.
+- [object_detection](object_detection): localizing and identifying multiple objects in a single image.
 - [real_nvp](real_nvp): density estimation using real-valued non-volume preserving (real NVP) transformations.
 - [resnet](resnet): deep and wide residual networks.
 - [skip_thoughts](skip_thoughts): recurrent neural network sentence-to-vector encoder.