[Rust] Crowdsourced Arrow Rust 4.0 Roadmap

[Andrew Lamb <al...@influxdata.com>]

As discussed on the Rust call today, please find below a link to a shared
document where anyone who plans to contribute to the 4.0 release of the
Arrow Rust implementation is welcomed to share what they plan to work on:

https://docs.google.com/document/d/1qspsOM_dknOxJKdGvKbC1aoVoO0M3i6x1CIo58mmN2Y/edit?usp=sharing

Please feel free to add new sections as suggestions or use the
collaboration features to ask additional questions.

Thank you,
Andrew

p.s here is the copy/pasted  introduction to give you a flavor of what is
going on:

Background and Purpose

Given the decentralized nature of Apache Arrow <https://arrow.apache.org/>
Rust development, different features are driven forward by various
contributors at different speeds dictated by their needs, interests and
available time.

We believe that sharing information across our community about plans for
the 4.0 release of Apache Arrow (~June 2021) will help focus our efforts
and more efficiently move the Apache Arrow Rust project forward.

We encourage anyone who plans to add functionality to the Rust Arrow
Implementation in the 4.0 timeline to add a section below. Doing so is
purely voluntary and not required prior to pull requests being considered