docs: update readme

* add badges
* add usage block

README.md

@@ -1,2 +1,17 @@
-# ssh-proxy
-Dockerized ssh-proxy
+# SSH-proxy
+
+> Dockerized ssh-proxy powered by OpenSSH
+
+[![](https://images.microbadger.com/badges/image/alebabai/ssh-proxy.svg)](https://microbadger.com/images/alebabai/ssh-proxy "Get your own image badge on microbadger.com")
+[![](https://images.microbadger.com/badges/version/alebabai/ssh-proxy.svg)](https://microbadger.com/images/alebabai/ssh-proxy "Get your own version badge on microbadger.com")
+[![](https://images.microbadger.com/badges/license/alebabai/ssh-proxy.svg)](https://microbadger.com/images/alebabai/ssh-proxy "Get your own license badge on microbadger.com")
+
+## Usage
+
+### Environment variables
+
+- `ADDRESS` - _provide one or more `HOST:PORT` pairs separated by space for services to be exposed_
+
+### Docker
+
+Here is docker-compose example configuration [`docker-compose.example.yml`](docker-compose.example.yml).