docs(python): Add docstring examples for various functions

[montanarograziano]

Related to: Add missing docstring examples #13161

Add example for:

• https://docs.pola.rs/py-polars/html/reference/api/polars.read_parquet_schema.html
• https://docs.pola.rs/py-polars/html/reference/api/polars.read_avro.html
• https://docs.pola.rs/py-polars/html/reference/api/polars.read_parquet_schema.html
• https://docs.pola.rs/py-polars/html/reference/api/polars.scan_ndjson.html
• https://docs.pola.rs/py-polars/html/reference/api/polars.build_info.html

[montanarograziano]

I see that tests are failing due to GHA errors, should I do something about it?