arrow

MINOR: [Python][Docs] Fix a code example rendering (#37557)

Add the required empty line before a code example of binary.

### Rationale for this change

The last code example of [pyarrow.binary](https://arrow.apache.org/docs/python/generated/pyarrow.binary.html#pyarrow.binary) was not rendered correctly in documentation.

### What changes are included in this PR?

Added one line break to make the code example render correctly.

### Are these changes tested?

No

### Are there any user-facing changes?

[pyarrow.binary](https://arrow.apache.org/docs/python/generated/pyarrow.binary.html#pyarrow.binary) documentation only.

Authored-by: Tero Vuotila <tero.vuotila@falcony.io>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>