message: Fix Optional type hints in Readme
diff: @@ -134,8 +134,8 @@ Run the SQL query, download the data from database into a Pandas dataframe.
  - `protocol: str = "binary"`: The protocol used to fetch data from source, default is `binary`. Check out [here](Types.md) to see more details.
  - `partition_on: Optional[str]`: The column to partition the result.
  - `partition_range: Optional[Tuple[int, int]]`: The value range of the partition column.
  -- `partition_num: Optioinal[int]`: The number of partitions to generate.
  -- `index_col: Optioinal[str]`: The index column to set for the result dataframe. Only applicable when `return_type` is `pandas`, `modin` or `dask`.
  +- `partition_num: Optional[int]`: The number of partitions to generate.
  +- `index_col: Optional[str]`: The index column to set for the result dataframe. Only applicable when `return_type` is `pandas`, `modin` or `dask`.
  ## Examples
  - Read a DataFrame from a SQL using a single thread
  