update changelog

CHANGELOG.md

@@ -26,5 +26,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * implement `From<(&'static str, Cow<'static, str)>` for `Attribute`
 * implement `From<&'static str>` and `From<String>` for `Element`
 * implement `From<[Element; N]>` and `From<Vec<Element>>` for `Element` (group elements without wrapping them in a `div`)
+* Support for `no_std` (by disabling the `std` feature flag)
+* Feature flags
+  * `std`: Enabled by default. Disable it to compile to `no_std`
+  * `rocket_v05` : implement [`rocket::response::Responder`](https://docs.rs/rocket/latest/rocket/response/trait.Responder.html) for `Document` and `Element` (for rocket 0.5)
 
 [Unreleased]: https://github.com/jcornaz/fun-html/compare/...HEAD