doc: move available assertions chapter from readme to own file

Cargo.toml

@@ -6,6 +6,7 @@ license = "MIT OR Apache-2.0"
 edition = "2024"
 rust-version = "1.88.0"
 repository = "https://github.com/innoave/asserting"
+readme = "docs/cratesio/README.md"
 
 description = """
 Fluent assertions for tests in Rust that are convenient to write and easy to extend.

build.rs

@@ -0,0 +1,26 @@
+//! This file is used to generate the README.md file for crates.io.
+#![allow(clippy::expect_used)]
+
+const README_PATH: &str = "README.md";
+const CRATESIO_README_PATH: &str = "docs/cratesio/README.md";
+const REPOSITORY_URL: &str = "https://github.com/innoave/asserting/tree/v";
+
+use std::{env, fs};
+
+fn main() {
+    rewrite_readme_for_cratesio_with_absolute_urls();
+}
+
+fn rewrite_readme_for_cratesio_with_absolute_urls() {
+    let version = env::var("CARGO_PKG_VERSION").expect("CARGO_PKG_VERSION must be set");
+
+    println!("cargo:rerun-if-changed={README_PATH}");
+
+    if let Ok(content) = fs::read_to_string(README_PATH) {
+        let target_url = format!("]({REPOSITORY_URL}{version}/docs/");
+        let updated_content = content.replace("](docs/", &target_url);
+
+        // Write README with absolute URLs for crates.io
+        let _ = fs::write(CRATESIO_README_PATH, updated_content);
+    }
+}