add: update README

README.md

@@ -1,31 +1,79 @@
 # OffBroadway.EMQTT
 
-## Building
+![pipeline status](https://github.com/Intility/off_broadway_emqtt/actions/workflows/elixir.yaml/badge.svg?event=push&branch=main)
+[![Hex Docs](https://img.shields.io/badge/hex-docs-blue.svg?style=plastic)](https://hexdocs.pm/off_broadway_emqtt/readme.html)
 
-By default, `:emqtt` compiles the `Quic` library. It is possible to build without by setting the environment variable
-`BUILD_WITHOUT_QUIC=1`.
+An MQTT connector based on [emqtt](https://github.com/emqx/emqtt) for [Broadway](https://github.com/dashbitco/broadway).
 
-``` shell
-BUILD_WITHOUT_QUIC=1 mix compile
-```
+## Usage
 
+``` elixir
+defmodule MyBroadway do 
+  use Broadway
+  alias Broadway.Message
+  def start_link(_opts) do 
+    Broadway.start_link(__MODULE__,
+      name: __MODULE__,
+      producer: [
+        module: {OffBroadway.EMQTT.Producer, 
+           buffer_size: 10_000,
+           buffer_overflow_strategy: :drop_head,
+           topics: [
+             {"test/topic1", :exactly_once},
+             {"test/topic2", :at_most_once},
+             {"test/topic3", :at_least_once},
+           ],
+           config: [
+             host: "test.mosquitto.org",
+             port: 1884,
+             username: "rw",
+             password: "readwrite"
+           ]
+        },
+        concurrency: 5
+      ],
+      processors: [
+        default: [concurrency: 10]
+      ],
+      batchers: [
+        default: [
+          batch_size: 200,
+          concurrency: 5 
+        ]
+      ]
+    )
+  end
+
+  @impl true
+  def handle_message(_, %Message{} = message, _) do 
+    IO.inspect(message, label: "Handled message from producer")
+  end
+
+  def handle_batch(_, messages, _, _) do 
+    IO.inspect("Received a batch of #{length(messages)} messages", label: "Handled batch from producer")
+    messages
+  end
+end
+```
 
-**TODO: Add description**
 
 ## Installation
 
-If [available in Hex](https://hex.pm/docs/publish), the package can be installed
+This package is [available in Hex](https://hex.pm/packages/off_broadway_emqtt), and can be installed
 by adding `off_broadway_emqtt` to your list of dependencies in `mix.exs`:
 
 ```elixir
 def deps do
   [
-    {:off_broadway_emqtt, "~> 0.1.0", system_env: [{"BUILD_WITHOUT_QUIC", "1"}]}
+    {:off_broadway_emqtt, "~> 0.1.0"}
   ]
 end
 ```
 
-Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
-and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
-be found at <https://hexdocs.pm/off_broadway_emqtt>.
+By default, `:emqtt` compiles the `Quic` library. It is possible to build without by setting the environment variable
+`BUILD_WITHOUT_QUIC=1`.
+
+``` shell
+BUILD_WITHOUT_QUIC=1 mix deps.compile
+```