feat(Renderer): update interface functions to start supporting buffered rendering

src/widget.zig

@@ -1,5 +1,5 @@
 //! Dynamic dispatch for widget implementations.
-//! Each widget should at last implement these functions:
+//! Each widget should at least implement these functions:
 //! - handle(this: *@This(), event: Event) ?Event {}
 //! - render(this: *@This(), renderer: *Renderer) !void {}
 //! - deinit(this: *@This()) void {}