update the dioxus cratesio readme, add many more examples (#5501)

* update the dioxus cratesio readme

* fix example

* fix header

* add a bunch more examples

examples/02-building-ui/counter.rs

@@ -0,0 +1,22 @@
+//! The classic counter — the "hello world" of reactive UI.
+//!
+//! `use_signal` creates a reactive value. Whenever the signal changes, any part of the UI
+//! that reads it will re-render automatically. Signals are copy-cheap, so you can freely
+//! move them into event handlers and closures.
+
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus::launch(app);
+}
+
+fn app() -> Element {
+    let mut count = use_signal(|| 0);
+
+    rsx! {
+        h1 { "Count: {count}" }
+        button { onclick: move |_| count += 1, "Increment" }
+        button { onclick: move |_| count -= 1, "Decrement" }
+        button { onclick: move |_| count.set(0), "Reset" }
+    }
+}