`sink_ndjson()` doesn't appear in docs

[etiennebacher]

Description

sink_ndjson() doesn't appear on the docs website, but it was implemented a few weeks ago in #10786.

Link

https://docs.pola.rs/docs/python/dev/search.html?q=ndjson

[cmdlineluser]

I think it just needs to be added here:

https://github.com/pola-rs/polars/blob/67507fffbff54679a4ff0e11f602b41e3ad6b99f/py-polars/docs/source/reference/io.rst?plain=1#L55-L58

[etiennebacher]

In addition to this, the function on the Python side is called sink_ndjson() but it is called sink_json() on the Rust side. Also, the example is wrong because it calls .sink_json(). Is this distinction between ndjson and json on purpose?

https://github.com/pola-rs/polars/blob/67507fffbff54679a4ff0e11f602b41e3ad6b99f/py-polars/polars/lazyframe/frame.py#L2227-L2228