parquet docs clarification
Would someone please clarify what is meant by the description for the `engine` arg to [`DataFrame.to_parquet`](https://pandas.pydata.org/pandas-docs/version/0.21/generated/pandas.DataFrame.to_parquet.html)?

```
engine : {‘auto’, ‘pyarrow’, ‘fastparquet’}, default ‘auto’

Parquet reader library to use. If ‘auto’, then the option ‘io.parquet.engine’ is used.
If ‘auto’, then the first library to be installed is used.
```

I think this description refers to the logic given here:

https://github.com/pandas-dev/pandas/blob/a00154dcfe5057cb3fd86653172e74b6893e337d/pandas/io/parquet.py#L11-L28


Based on the code, should it read as follows?
```
engine : {‘auto’, ‘pyarrow’, ‘fastparquet’}, default ‘auto’

Parquet reader library to use. If ‘auto’, then the option ‘io.parquet.engine’ is used.
If ‘io.parquet.engine’ is not set, then the first library to be installed is used.
```