docs: missing to_parquet() docs

[ncclementi]

Please describe the issue

xref zulip: https://ibis-project.zulipchat.com/#narrow/stream/405265-tech-support/topic/specify.20partition.20columns.20in.20to_parquet.28.29.3F/near/451643876

We have docstrings but I wasn't able to find this rendered, is this intentional because it's experimental or they are somehow missing?

ibis/ibis/expr/types/core.py

Lines 568 to 604 in f50cbfc

	"""Write the results of executing the given expression to a parquet file.
	This method is eager and will execute the associated expression
	immediately.
	Parameters
	----------
	path
	The data source. A string or Path to the parquet file.
	params
	Mapping of scalar parameter expressions to value.
	**kwargs
	Additional keyword arguments passed to pyarrow.parquet.ParquetWriter
	https://arrow.apache.org/docs/python/generated/pyarrow.parquet.ParquetWriter.html
	Examples
	--------
	Write out an expression to a single parquet file.
	>>> import ibis
	>>> import tempfile
	>>> penguins = ibis.examples.penguins.fetch()
	>>> penguins.to_parquet(tempfile.mktemp())
	Partition on a single column.
	>>> penguins.to_parquet(tempfile.mkdtemp(), partition_by="year")
	Partition on multiple columns.
	>>> penguins.to_parquet(tempfile.mkdtemp(), partition_by=("year", "island"))
	::: {.callout-note}
	## Hive-partitioned output is currently only supported when using DuckDB
	:::
	"""

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[gforsyth]

so a bunch of these are rendered in the backend docs pages, but aren't showing up in Algolia. I'm going to try to add them to our additional algolia index scrape script.