read.csv index_col argument accepts string, list-of-string
1. `read.csv` index_col argument has been accepting either string or list-of-string for years, but the doc (as of 0.24 dev) has never been updated to reflect this. Current and suggested text at bottom.
1. All columns used in index_col get dropped as regular columns. The doc never explicitly says this and [it causes user confusion](https://stackoverflow.com/questions/51794078/python-the-label-is-not-in-the-columns-error-after-pd-read-csv-index-col).
1. The doc does however discuss "malformed file with delimiters at the end of each line... you might consider index_col=False", this is overly prominent for a rare defective case and should be shunted somewhere less prominent, or at minimum relegated to a parenthesized footnote.

Current read.csv doc:

> index_col : _int or sequence or `False`, default `None`_
> Column to use as the row labels of the DataFrame. If a sequence is given, a MultiIndex is used. If you have a malformed file with delimiters at the end of each line, you might consider index_col=False to force pandas to not use the first column as the index (row names).

Suggested read.csv doc:

> index_col : _int/string or sequence of int/string or `False`, default `None`_
> Column(s) to use as the row labels of the DataFrame, either given as string name or column index.
> If a sequence of int/string is given, a MultiIndex is used.
> Columns used for the index (row names) are dropped from the actual columns of the input dataframe. (They are accessible via `.index`).
> (Note: `index_col=False` can be used to force pandas to not use the first column as the index, e.g. when you have a malformed file with delimiters at the end of each line).