fix duplicate example names

packages/dioxus-tui/examples/readme_hello_world.rs

@@ -0,0 +1,19 @@
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus_tui::launch(app);
+}
+
+fn app(cx: Scope) -> Element {
+    cx.render(rsx! {
+        div {
+            width: "100%",
+            height: "10px",
+            background_color: "red",
+            justify_content: "center",
+            align_items: "center",
+
+            "Hello world!"
+        }
+    })
+}