Fix comment

Author: blyxyas

clippy_lints/src/functions/must_use.rs

@@ -115,7 +115,7 @@ fn check_needless_must_use(
             },
         );
     } else if attr.value_str().is_none() && is_must_use_ty(cx, return_ty(cx, item_id)) {
-        // Ignore normal
+		// Ignore async functions unless Future::Output type is a must_use type
         if sig.header.is_async() {
             let infcx = cx.tcx.infer_ctxt().build();
             if let Some(future_ty) = infcx.get_impl_future_output_ty(return_ty(cx, item_id))