Update readme

README.md

@@ -6,6 +6,6 @@ Dependency can be installed via `pip install -r requirements.txt`.
 If version conflicts occur, use requirements_fixed_version.txt.
 
 # Datasets
-Some datasets are too large to include in the repository. 
-The notebooks contain information about possible download
-location within the corresponding cells. 
+For further analysis the sentiment140 dataset can be downloaded and put into the
+`sentiment_test_sets` folder. The notebook `Classification Similarity Correlation.ipynb`
+contains all necessary information. The file is not required for the execution of any example. 
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