fix: Update doc links from v3 to v4

packages/dioxus/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2021"
 description = "Portable, performant, and ergonomic framework for building cross-platform user interfaces in Rust"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/DioxusLabs/dioxus/"
-homepage = "https://dioxuslabs.com/docs/0.3/guide/en/index.html"
+homepage = "https://dioxuslabs.com/learn/0.4/"
 keywords = ["dom", "ui", "gui", "react", "wasm"]
 rust-version = "1.65.0"