read_csv reference cites two different default delimiters
In the [reference for the pandas.read_csv function ](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_csv.html), the prototype function shows that the default value for sep is `sep=', ',` (notice the space after the comma).

In the detailed description, it says that the default is 

> `sep : str, default ‘,’`

with no space after the comma, which is how the function behaves (comma space separators lead to columns with leading whitespace).

I would have done this as a pull request but I couldn't find the source for the doc page.