Rust version policy: Add note about stable/LTS kernels

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

Author: ojeda

src/Rust-version-policy.md

@@ -2,7 +2,7 @@
 
 ## Supported versions
 
-The kernel documents the [minimal requirements](https://docs.kernel.org/process/changes.html) to compile it. Since v6.11, the kernel supports a minimum version of Rust. The initial minimum was Rust 1.78.0, and the next one will be Rust 1.85.0 (expected in Linux v7.1), following Debian 13 (Trixie)'s Rust toolchain version — please see ["Minimum upgrade policy"](Rust-version-policy.md#minimum-upgrade-policy) below for details.
+The kernel documents the [minimal requirements](https://docs.kernel.org/process/changes.html) to compile it. Since v6.11, the kernel supports a minimum version of Rust. The initial minimum was Rust 1.78.0, and the next one will be Rust 1.85.0 (expected in Linux v7.1)[^stable-kernels], following Debian 13 (Trixie)'s Rust toolchain version — please see ["Minimum upgrade policy"](Rust-version-policy.md#minimum-upgrade-policy) below for details.
 
 For the moment, we cannot guarantee newer Rust versions will always work due to the [unstable features](Unstable-features.md) in use[^rust-is-stable]. Removing the need for them is a priority of the project.
 
@@ -12,6 +12,8 @@ Thus, with the pre-merge CIs in place, those projects hope to avoid unintentiona
 
 In addition, getting Linux to build on stable Rust has been a "flagship goal" of the Rust project for [2024H2](https://rust-lang.github.io/rust-project-goals/2024h2/rfl_stable.html) and [2025H1](https://rust-lang.github.io/rust-project-goals/2025h1/rfl.html). We also have two ongoing goals for 2025H2: [language](https://rust-lang.github.io/rust-project-goals/2025h2/Rust-for-Linux-language.html) and [compiler](https://rust-lang.github.io/rust-project-goals/2025h2/Rust-for-Linux-compiler.html).
 
+[^stable-kernels]: Stable/LTS kernels may have different requirements. For instance, Linux 6.18.y has a minimum of Rust 1.78.0 at the time of writing.
+
 [^rust-is-stable]: To clarify, the Rust language is stable, i.e. it promises backwards compatibility, except for those unstable features.
 
 ## Supported toolchains