Yes, you're right. Thanks for the heads up! I have updated that part:

The thresh parameter requires a row or column to have at least the specified number of non-missing values not to be dropped. For instance, if we set the value of the thresh parameter as 3, a column or row must have at least 3 non-missing values not to be dropped. The rows or columns (depending on the value of the axis parameter) that do not have 3 or more non-missing values will be dropped.