Mention Rust support and add hello world Rust example

.reuse/dep5

@@ -5,6 +5,8 @@ Source: http://sel4.systems
 
 Files:
   tool/microkit/Cargo.lock
+  example/rust/Cargo.lock
+  example/rust/support/*.json
   flake.lock
   CHANGES.md
   VERSION

docs/manual.md

@@ -396,6 +396,16 @@ The report can be useful when debugging potential system problems.
 This report does not have a fixed format and may change between versions.
 It is not intended to be machine readable.
 
+# Language Support
+
+There are native APIs for C/C++ and Rust.
+
+[libmicrokit](#libmicrokit) exports a C API and so can be used in any language
+that supports C FFI.
+
+For Rust, native bindings exist but are not included in the SDK itself. They are
+available at [rust-sel4](https://github.com/seL4/rust-sel4).
+
 # libmicrokit {#libmicrokit}
 
 All program images should link against `libmicrokit.a`.

example/rust/.cargo/config.toml

@@ -0,0 +1,11 @@
+#
+# Copyright 2023, Colias Group, LLC
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+
+[unstable]
+unstable-options = true
+
+[env]
+RUST_TARGET_PATH = { value = "support/targets", relative = true }