text: Title: Typo in Docs: atrrs not an argument of visualize_tokens function(attrs rather) 
  Body: Awesome tool @ines . Just a slight typo in the docs for the `visualize_tokens()` function.
  In the example  `attrs` is spelt as `atrrs`. We need to make some slight changes.
  
  ![Screenshot from 2020-07-09 13-42-50](https://user-images.githubusercontent.com/21055925/87031024-1b6fab80-c1eb-11ea-9d03-2e3de1eab48b.png)
    
  Great Work!!. Thanks