docs(channel): clarify feature boundaries

[tisonkun]

Summary

• Keep the existing mpsc Cargo feature instead of introducing a speculative queue, dispatch, or channel aggregate.
• Document that current channel features follow current public modules: oneshot, mpsc, and broadcast; topology and capacity remain API-level choices.
• Separate one-shot, single-delivery MPSC, and broadcast entries in the API guide.
• Correct the changelog wording: broadcast::overflow was removed, while the broadcast feature remains.

Design Notes

Cargo features control compiled capabilities and dependencies; they do not need to encode every channel topology. The broadcast feature can expose specialized SPMC and MPMC APIs under one delivery family, while implementation-specific producer topology remains visible in module paths and types. Additional aggregate or leaf features should be introduced only when implemented variants demonstrate a material compile-time, dependency, binary-size, or audit boundary.

Refs #167 and #206.

Validation: cargo x check, cargo x build, cargo x lint, cargo x test, and cargo +1.86.0 check -p asyncband --no-default-features --features mpsc.

[Copilot]

Pull request overview

Clarifies how Asyncband’s channel-related Cargo features map to the public API surface (by delivery family modules), and updates the crate-level API guide and changelog wording to match that framing.

Changes:

• Document that channel Cargo features align with the public modules oneshot, mpsc, and broadcast, with topology/capacity expressed in module paths and constructors.
• Split the crate-level API guide’s “Send values” row into distinct oneshot/MPSC/broadcast entries for clearer boundaries.
• Adjust changelog wording around the removal of broadcast::overflow vs. retention of the broadcast feature.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
README.md	Adds a channel-features clarification and tightens the MPSC description in the API table.
CHANGELOG.md	Updates wording about broadcast::overflow removal and the remaining broadcast feature.
asyncband/src/lib.rs	Expands crate docs to clarify feature boundaries and separates channel families in the API guide table.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.