[Docs][Python] Narrow Feather deprecation to V1 format #50808

Describe the bug, including details regarding any error messages, version, and platform.

#49590 deprecated the complete pyarrow.feather API, causing write_feather(), read_feather(), read_table(), and FeatherDataset to emit warnings even when using Feather V2.

The intended deprecation applies only to the Feather V1 format. Feather V2 is the Arrow IPC file format and remains supported. The pyarrow.feather APIs also provide conveniences, such as one-call reading and writing and column selection by name, for which pyarrow.ipc does not yet provide direct equivalents.

This is a follow-up to #49590 and the discussion in #49232 (comment).

Component(s)

Python, Documentation