add rewritten router book and fix features code

docs/router/src/features/history-providers.md

@@ -0,0 +1,44 @@
+# History Providers
+
+In order to provide the ability to traverse the navigation history, the router
+uses [`HistoryProvider`]s. Those implement the actual back-and-forth
+functionality.
+
+The router provides five [`HistoryProvider`]s, but you can also create your own.
+The five default implementations are:
+- The [`MemoryHistory`] is a custom implementation that works in memory.
+- The [`WebHistory`] integrates with the browsers URL.
+- The [`WebHashHistory`] also integrates with the browser, but uses the fragment
+  part of the URL.
+
+By default the router uses the [`MemoryHistory`]. It might be changed to use
+[`WebHistory`] when the `web` feature is active, but that is not guaranteed.
+
+You can override the default history:
+```rust,no_run
+# // Hidden lines (like this one) make the documentation tests work.
+# extern crate dioxus;
+use dioxus::prelude::*;
+# extern crate dioxus_router;
+use dioxus_router::{prelude::*, history::WebHashHistory};
+
+fn App(cx: Scope) -> Element {
+    use_router(
+        &cx,
+        &|| RouterConfiguration {
+            history: Box::new(WebHashHistory::new(true)),
+            ..Default::default()
+        },
+        &|| Segment::empty()
+    );
+
+    cx.render(rsx! {
+        Outlet { }
+    })
+}
+```
+
+[`HistoryProvider`]: https://docs.rs/dioxus-router-core/latest/dioxus_router_core/history/trait.HistoryProvider.html
+[`MemoryHistory`]: https://docs.rs/dioxus-router-core/latest/dioxus_router_core/history/struct.MemoryHistory.html
+[`WebHistory`]: https://docs.rs/dioxus-router-core/latest/dioxus_router_core/history/struct.WebHistory.html
+[`WebHashHistory`]: https://docs.rs/dioxus-router-core/latest/dioxus_router_core/history/struct.WebHashHistory.html