new categorization of fixes, test split statistics update

Update README.md

Updating description of fields and statistics

Update README.md

Update README.md

Adding notes about dataset

The description of the error typology has been brought into line with the actual contents of the error_type field

Update README.md

Update README.md

Update README.md

Updating statistics

Update README.md

Update README.md

Update README.md

Update README.md

Update README.md

Update README.md

Update README.md

Fixing typos in readme

Update README.md

initial commit