docs: more docs and an errorhandling example

examples/error_handle.rs

@@ -0,0 +1,22 @@
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus::desktop::launch(app);
+}
+
+fn app(cx: Scope) -> Element {
+    let val = use_state(&cx, || "0.0001");
+
+    let num = match val.parse::<f32>() {
+        Err(_) => return cx.render(rsx!("Parsing failed")),
+        Ok(num) => num,
+    };
+
+    cx.render(rsx! {
+        h1 { "The parsed value is {num}" }
+        button {
+            onclick: move |_| val.set("invalid"),
+            "Set an invalid number"
+        }
+    })
+}