docs: remove all usages of static closure syntax and update readme

examples/ssr.rs

@@ -2,16 +2,16 @@ use dioxus::prelude::*;
 use dioxus::ssr;
 
 fn main() {
-    let mut vdom = VirtualDom::new(APP);
+    let mut vdom = VirtualDom::new(app);
     let _ = vdom.rebuild();
     println!("{}", ssr::render_vdom(&vdom));
 }
 
-static APP: Component = |cx| {
+fn app(cx: Scope) -> Element {
     cx.render(rsx!(
         div {
             h1 { "Title" }
             p { "Body" }
         }
     ))
-};
+}