f add docs on wtf the types are

Author: TheBlueMatt

lightning/src/util/wakers.rs

@@ -212,6 +212,9 @@ impl Sleeper {
 	pub fn new(futures: Vec<Future>) -> Self {
 		Self { notifiers: futures.into_iter().map(|f| f.state).collect() }
 	}
+	/// Prepares to go into a wait loop body, creating a condition variable which we can block on
+	/// and an `Arc<Mutex<Option<_>>>` which gets set to the waking `Future`'s state prior to the
+	/// condition variable being woken.
 	fn setup_wait(&self) -> (Arc<Condvar>, Arc<Mutex<Option<Arc<Mutex<FutureState>>>>>) {
 		let cv = Arc::new(Condvar::new());
 		let notified_fut_mtx = Arc::new(Mutex::new(None));