add readme

README.md

@@ -0,0 +1,31 @@
+# nanoev
+
+A minimalistic but modular abstraction for IO event loops.
+
+The goal of this library is to provide a uniform abstraction over multiple
+system event loops, in a way that plays well with Picos.
+
+## Usage
+
+Very basic usage would look like this:
+
+```ocaml
+module EV = Nanoev_picos
+
+
+let () =
+  (* use a backend, eg. select *)
+  let ev = Nanoev_unix.create () in
+
+  (* install the backend *)
+  Nanoev_picos.setup_bg_thread ev;
+
+  (* setup a picos scheduler and use EV.read, EV.write, etc. *)
+  …
+```
+
+
+## Backends
+
+- [x] select
+- [ ] uring