Document planned release cadence for arrow/parquet/etc (#5737)

* Document planned release cadence

* add bandwidth note

* add links to main readme

* prettier

* Update README.md

* Update README.md

Co-authored-by: Raphael Taylor-Davies <1781103+tustvold@users.noreply.github.com>

---------

Co-authored-by: Raphael Taylor-Davies <1781103+tustvold@users.noreply.github.com>

README.md

@@ -34,7 +34,33 @@ This repo contains the following main components:
 
 The current development version the API documentation in this repo can be found [here](https://arrow.apache.org/rust).
 
-There are two related crates in a different repository
+## Release Versioning and Schedule
+
+The Arrow Rust project releases approximately monthly and follows [Semantic
+Versioning](https://semver.org/).
+
+Due to available maintainer and testing bandwidth, `arrow` crates (`arrow`,
+`arrow-flight`, etc.) are released on the same schedule with the same versions
+as the `parquet` and `parquet-derive` crates.
+
+Starting June 2024, we plan to release new major versions with potentially
+breaking API changes at most once a quarter, and release incremental minor versions in
+the intervening months. See [this ticket] for more details.
+
+For example:
+
+| Approximate Date | Version  | Notes                                   |
+| ---------------- | -------- | --------------------------------------- |
+| Jun 2024         | `52.0.0` | Major, potentially breaking API changes |
+| Jul 2024         | `52.1.0` | Minor, NO breaking API changes          |
+| Aug 2024         | `52.2.0` | Minor, NO breaking API changes          |
+| Sep 2024         | `53.0.0` | Major, potentially breaking API changes |
+
+[this ticket]: https://github.com/apache/arrow-rs/issues/5368
+
+## Related Projects
+
+There are two related crates in different repositories
 
 | Crate      | Description                             | Documentation                 |
 | ---------- | --------------------------------------- | ----------------------------- |

arrow/README.md

@@ -35,9 +35,18 @@ This crate is tested with the latest stable version of Rust. We do not currently
 
 ## Versioning / Releases
 
-The arrow crate follows the [SemVer standard](https://doc.rust-lang.org/cargo/reference/semver.html) defined by Cargo and works well within the Rust crate ecosystem.
-
-However, for historical reasons, this crate uses versions with major numbers greater than `0.x` (e.g. `39.0.0`), unlike many other crates in the Rust ecosystem which spend extended time releasing versions `0.x` to signal planned ongoing API changes. Minor arrow releases contain only compatible changes, while major releases may contain breaking API changes.
+The `arrow` crate follows the [SemVer standard] defined by Cargo and works well
+within the Rust crate ecosystem. See the [repository README] for more details on
+the release schedule and version.
+
+[SemVer standard]: https://doc.rust-lang.org/cargo/reference/semver.html
+[repository README]: https://github.com/apache/arrow-rs
+
+Note that for historical reasons, this crate uses versions with major numbers
+greater than `0.x` (e.g. `19.0.0`), unlike many other crates in the Rust
+ecosystem which spend extended time releasing versions `0.x` to signal planned
+ongoing API changes. Minor arrow releases contain only compatible changes, while
+major releases may contain breaking API changes.
 
 ## Feature Flags
 

parquet/README.md

@@ -34,9 +34,18 @@ This crate is tested with the latest stable version of Rust. We do not currently
 
 ## Versioning / Releases
 
-The arrow crate follows the [SemVer standard](https://doc.rust-lang.org/cargo/reference/semver.html) defined by Cargo and works well within the Rust crate ecosystem.
-
-However, for historical reasons, this crate uses versions with major numbers greater than `0.x` (e.g. `19.0.0`), unlike many other crates in the Rust ecosystem which spend extended time releasing versions `0.x` to signal planned ongoing API changes. Minor arrow releases contain only compatible changes, while major releases may contain breaking API changes.
+The `parquet` crate follows the [SemVer standard] defined by Cargo and works well
+within the Rust crate ecosystem. See the [repository README] for more details on
+the release schedule and version.
+
+[semver standard]: https://doc.rust-lang.org/cargo/reference/semver.html
+[repository readme]: https://github.com/apache/arrow-rs
+
+Note that for historical reasons, this crate uses versions with major numbers
+greater than `0.x` (e.g. `19.0.0`), unlike many other crates in the Rust
+ecosystem which spend extended time releasing versions `0.x` to signal planned
+ongoing API changes. Minor arrow releases contain only compatible changes, while
+major releases may contain breaking API changes.
 
 ## Feature Flags