Rust version policy: Update distributions from upstream docs after the minimum bump

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: ojeda

src/Rust-version-policy.md

@@ -22,9 +22,9 @@ The Rust versions currently supported should already be enough for kernel develo
   - Debian 13 (Trixie), Debian Testing and Debian Unstable (Sid).
   - Fedora Linux.
   - Gentoo Linux.
-  - Nix (unstable).
-  - openSUSE Slowroll and Tumbleweed.
-  - Ubuntu LTS (20.04, 22.04, 24.04) and non-LTS (interim).
+  - Nix.
+  - openSUSE Slowroll and openSUSE Tumbleweed.
+  - Ubuntu 25.10 and 26.04 LTS. In addition, 24.04 LTS with versioned packages.
 
 In addition, we support the toolchains distributed by Rust, installed via [`rustup`](https://rust-lang.github.io/rustup/) or the [standalone installers](https://forge.rust-lang.org/infra/other-installation-methods.html#standalone-installers).