Added small documentation

README.md

@@ -1,3 +1,52 @@
 # container.js
 
 Microscopic dependency injection container
+
+## Installation
+
+    yarn add elao-container.js
+
+## Usage
+
+Given the given class, you want to declare as a service:
+
+```js
+// MyApiClient.js
+export default class MyApiClient {
+    constructor(host, key) {
+        this.host = host;
+        this.key keyhost;
+    }
+
+    login() {
+        // ...
+    }
+}
+```
+
+Set up your container like that:
+
+```js
+// my-container.js
+import Container from 'elao-container.js';
+import MyApiClient from './MyApiClient';
+
+const container = new Container();
+
+// Register a parameter:
+container.registerParameter('api:host', 'my.api.com');
+container.registerParameter('api:key', 'xxxxxxxxxxx');
+
+// Register a service:
+container.registerDefinition('api', MyApiClient, ['api:host', 'api:key']);
+
+export default container;
+```
+
+Require the `api` service wherever you need it:
+
+```js
+import container from 'my-container.js';
+
+container.fetch('api').login();
+```