feat(docs): Improved shared state, use_effect and use_memo docs

docs/guide/src/en/interactivity/memoization.md

@@ -0,0 +1,23 @@
+# Memoization
+
+[`use_memo`](https://docs.rs/dioxus-hooks/latest/dioxus_hooks/fn.use_memo.html) let's you memorize values and therefore save computation time. This is useful for expensive calculations.
+
+```rust, no_run
+#[inline_props]
+fn Calculator(cx: Scope, number: usize) -> Element {
+    let bigger_number = use_memo(cx, (number,), |(number,)| {
+        // This will only be calculated when `number` has changed.
+        number * 100
+    }):
+
+    render!(
+        p { "{bigger_number}" }
+    )
+}
+
+fn app(cx: Scope) -> Element {
+    render!(
+        Calculator { number: 0 }
+    )
+}
+```