docs: Clarify support policy

Author: epage

CONTRIBUTING.md

@@ -65,8 +65,8 @@ As we work towards [a more flexible architecture](https://github.com/clap-rs/cla
 | Version                                              | Status        | Support | End-of-Life |
 |------------------------------------------------------|---------------|---------|-------------|
 | [v4](https://github.com/clap-rs/clap/tree/master)    | active        | Features and bug fixes target `master` by default | TBD |
-| [v3](https://github.com/clap-rs/clap/tree/v3-master) | maintenance   | Accepting trivial cherry-picks from `master` (i.e. minimal conflict resolution) by contributors | TBD |
-| [v2](https://github.com/clap-rs/clap/tree/v2-master) | deprecated    | Only accepting fixes for ecosystem-wide critical bugs | TBD |
+| [v3](https://github.com/clap-rs/clap/tree/v3-master) | maintenance   | Accepting trivial cherry-picks from `master` (i.e. minimal conflict resolution) by contributors and fixes for ecosystem-wide showstoppers | TBD |
+| [v2](https://github.com/clap-rs/clap/tree/v2-master) | deprecated    | Only accepting fixes for ecosystem-wide showstoppers | TBD |
 | v1                                                   | unsupported   | \- | \- |
 
 Note: We have not yet determined the End-of-Life schedule for previous major versions.  We will give at least a 2 month warning before changing the support status.