Internationalization: move guide to en folder and preserve its history. (#494)

* chore: move guide to en folder

* docs: add english as language

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

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+
+## Memoization
+
+Dioxus uses Memoization for a more efficient user interface. Memoization is the process in which we check if a component actually needs to be re-rendered when its props change. If a component's properties change but they wouldn't affect the output, then we don't need to re-render the component, saving time!
+
+For example, let's say we have a component that has two children:
+
+```rust
+fn Demo(cx: Scope) -> Element {
+    // don't worry about these 2, we'll cover them later
+    let name = use_state(&cx, || String::from("bob"));
+    let age = use_state(&cx, || 21);
+
+    cx.render(rsx!{
+        Name { name: name }
+        Age { age: age }
+    })
+}
+```
+
+If `name` changes but `age` does not, then there is no reason to re-render our `Age` component since the contents of its props did not meaningfully change.
+
+Dioxus memoizes owned components. It uses `PartialEq` to determine if a component needs rerendering, or if it has stayed the same. This is why you must derive PartialEq!
+
+> This means you can always rely on props with `PartialEq` or no props at all to act as barriers in your app. This can be extremely useful when building larger apps where properties frequently change. By moving our state into a global state management solution, we can achieve precise, surgical re-renders, improving the performance of our app.
+
+Borrowed Props cannot be safely memoized. However, this is not a problem – Dioxus relies on the memoization of their parents to determine if they need to be rerendered.
+