chore: add readme

Author: dancixx

README.md

@@ -0,0 +1,46 @@
+# async-safe-defer
+
+Minimal async- and sync-capable `defer` crate with:
+
+- ✅ async support
+- ✅ no `unsafe` code
+- ✅ `no_std` + `alloc` compatible
+- ✅ optional `no_alloc` mode
+- ✅ zero dependencies
+
+Inspired by [`defer`](https://crates.io/crates/defer), but designed for embedded and async contexts.
+
+## Usage
+
+### Sync
+```rust
+use async_defer::defer;
+
+fn main() {
+    defer!(println!("cleanup"));
+    println!("work");
+}
+```
+
+### Async
+```rust
+use async_defer::async_scope;
+
+async_scope!(scope, {
+    scope.defer(|| async { println!("async cleanup") });
+    println!("async work");
+}).await;
+```
+
+### No-alloc
+```rust
+use async_defer::no_alloc::AsyncScopeNoAlloc;
+
+fn task() -> Pin<Box<dyn Future<Output = ()> + 'static>> {
+    Box::pin(async { println!("no_alloc") })
+}
+
+let mut scope = AsyncScopeNoAlloc::<2>::new();
+scope.defer(task);
+scope.run().await;
+```