[data request] APTOS 2019 Blindness Detection

• Name of dataset: APOTOS 2019 Blindness Detection - for diabetic retinopathy
• URL of dataset: https://www.kaggle.com/c/aptos2019-blindness-detection/overview
• License of dataset: Apache License 2.0
• Short description of dataset and use case(s):
  The dataset contains retina images taken using fundus photography under a variety of imaging conditions. The dataset is mainly used to study the severity of diabetic retinopathy on a scale of 0 to 4. Aravind Eye Hospital in India hopes to detect and prevent this disease among people living in rural areas where medical screening is difficult to conduct.

Folks who would also like to see this dataset in tensorflow/datasets, please thumbs-up so the developers can know which requests to prioritize.

And if you'd like to contribute the dataset (thank you!), see our guide to adding a dataset.

Start with docs/add_dataset.md and review the linked Kaggle dataset details, including its license and diabetic-retinopathy use case. Compare the request with existing dataset implementations in tensorflow/datasets; done means the APTOS 2019 Blindness Detection dataset is added according to the contribution guide and its data preparation and metadata are covered.