fixup! rust: Run all examples on stable

examples/rust-hello-world/Makefile

@@ -21,9 +21,9 @@ BASELIBS += $(APPLICATION_RUST_MODULE).module
 
 FEATURES_REQUIRED += rust_target
 
-# While this example can be built with stable Rust on many platforms, the
-# nightly channel is selected to smoothly transition from running this example
-# to experimenting with it (which might easily lead into nightly territory).
+# All Rust components RIOT uses work on stable Rust. If any extra libraries
+# were to require a more recent version, switch to `CARGO_CHANNEL =
+# $(CARGO_CHANNEL_NIGHTLY)` to use whichever nightly version is available.
 CARGO_CHANNEL ?= stable
 
 # Currently unknown, something related to the LED_PORT definition that doesn't