[Python][Docs] Add `pyarrow.parquet.filters_to_expression` to API reference docs

### Describe the enhancement requested

From the discussion in https://github.com/apache/arrow/discussions/47988, `pyarrow.parquet.filters_to_expression` feels useful enough me to be to be added to the public API reference docs.
I did not see it there at the moment (unless I made a mistake).

### Component(s)

Documentation