Add usage examples to README.md

Signed-off-by: John Else <john.else@gmail.com>

README.md

@@ -13,3 +13,41 @@ Dependencies:
 * [ocplib-endian](https://github.com/OCamlPro/ocplib-endian)
 * [oUnit](http://ounit.forge.ocamlcore.org/)
 * [rresult](https://github.com/dbuenzli/rresult)
+
+Usage
+=====
+
+If you just want to parse and serialise OSC packets, use the `Osc.Codec`
+module:
+
+``` ocaml
+# require "osc";;
+
+# open Osc.Types;;
+
+# let data = Osc.Codec.of_packet (Message {address = "/hello/world"; arguments = [Int32 123l; String "foo"]});;
+val data : bytes = "/hello/world\000\000\000\000,is\000\000\000\000{foo\000"
+
+# let packet = Osc.Codec.to_packet data;;
+val packet : (packet, [ `Missing_typetag_string | `Unsupported_typetag of char ]) Rresult.result =
+  Rresult.Ok (Message {address = "/hello/world"; arguments = [Int32 123l; String "foo"]})
+```
+
+To simplify sending and receiving OSC packets over the network, the modules
+`Osc_lwt` and `Osc_unix` are available:
+
+``` ocaml
+# require "osc.lwt";;
+
+# require "lwt.syntax";;
+
+# open Osc.Types;;
+
+# lwt client = Osc_lwt.Udp.Client.create ();;
+val client : Osc_lwt.Udp.Client.t = <abstr>
+
+# let addr = Unix.ADDR_INET (Unix.inet_addr_of_string "127.0.0.1", 57120);;
+val addr : Lwt_unix.sockaddr = Unix.ADDR_INET (<abstr>, 57120)
+
+# lwt () = Osc_lwt.Udp.Client.send client addr (Message {address = "/hello/world"; arguments = [Int32 123l; String "foo"]});;
+```