Typo in Indexing, Slicing & Subsetting episode

[Nel Swanepoel]

The Index, Slicing & Subsetting episode has a typo in the Copying Objects vs Referencing Objects in Python section.

The Python code snippet is

# Assign the value `0` to the first three rows of data in the DataFrame
ref_surveys_df[0:3] = 0

but then in the following text paragraph it is stated:

When we assigned the first 3 columns the value of 0

It should be

When we assigned the first 3 rows the value of 0

[Benjamin Tovar]

Fixed in #480