zephyr: Make alloc public

Although this module has no contents that are public, mark the module
itself as public so it can be a container for its documentation.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

zephyr/src/lib.rs

@@ -130,6 +130,7 @@ pub mod _export {
     pub use core::format_args;
 }
 
+// Mark this as `pub` so the docs can be read.
 /// If allocation has been requested, provide the allocator.
 #[cfg(CONFIG_RUST_ALLOC)]
-mod alloc;
+pub mod alloc;