text: Title: How to generate context embedding for DKN?[ASK] 
  Body: ### Description
  <!--- Describe your general ask in detail -->
  I notice that context embedding is not used in the [dkn_deep_dive.ipynb](https://github.com/microsoft/recommenders/blob/master/examples/02_model_content_based_filtering/dkn_deep_dive.ipynb). But as DKN article describes, context embedding can improve the quality of the model. I wonder how we can generate a context embedding for DKN using MIND dataset?  
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