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/04-managing-state/use_memo.rs

@@ -0,0 +1,39 @@
+//! Deriving values with `use_memo`.
+//!
+//! `use_memo` caches the result of a closure and re-runs it only when one of the signals
+//! it reads changes. It's how you compute values derived from state without doing the work
+//! on every render, and without introducing another `use_signal` that you have to keep
+//! in sync manually.
+
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus::launch(app);
+}
+
+fn app() -> Element {
+    let mut first = use_signal(|| "Ada".to_string());
+    let mut last = use_signal(|| "Lovelace".to_string());
+
+    // Recomputes only when `first` or `last` change
+    let full_name = use_memo(move || format!("{first} {last}"));
+
+    // Memos compose — derive from other memos or signals
+    let initials = use_memo(move || {
+        let name = full_name();
+        name.split_whitespace()
+            .filter_map(|w| w.chars().next())
+            .collect::<String>()
+    });
+
+    rsx! {
+        h1 { "{full_name}" }
+        p { "Initials: {initials}" }
+
+        label { "First: " }
+        input { value: "{first}", oninput: move |e| first.set(e.value()) }
+
+        label { "Last: " }
+        input { value: "{last}", oninput: move |e| last.set(e.value()) }
+    }
+}