arrow

MINOR: [Docs] Use endpoint_override in code example for minIO (#13436)

Current code snippet show how to configure connection to minIO appears to use wrong named argument for endpoint. Instead of `endpoint` it should be `endpoint_override`

see https://arrow.apache.org/docs/python/generated/pyarrow.fs.S3FileSystem.html

<img width="560" alt="image" src="https://user-images.githubusercontent.com/179870/175815553-18042907-1c9d-4cd1-8a3b-ef9a1284b4c8.png">


Authored-by: Jürgen Walter <juwalter@gmail.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>