Update README.md

Updated Git Checkout instructions

Author: leriomaggio

README.md

@@ -45,7 +45,8 @@
 
 ```
 
-git clone -b pydatalondon2017 https://github.com/leriomaggio/deep-learning-keras-tensorflow.git
+git clone https://github.com/leriomaggio/deep-learning-keras-tensorflow.git
+git checkout tags/pydata-london2017
 ```
 
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