Make example work on web and update READMEs

web/src/widget/button.rs

@@ -2,7 +2,7 @@ use crate::{Bus, Element, Widget};
 
 use dodrio::bumpalo;
 
-pub type Button<'a, Message> = iced_core::Button<'a, Message>;
+pub use iced_core::button::*;
 
 impl<'a, Message> Widget<Message> for Button<'a, Message>
 where
@@ -29,6 +29,8 @@ where
             });
         }
 
+        // TODO: Complete styling
+
         node.finish()
     }
 }