Document standalone usage

README.md

@@ -21,7 +21,9 @@ $ npm install concurrency-logger
 ```
 
 ## Usage
+
 ### With [koa](https://github.com/koajs/koa)
+
 #### Basic usage
 ```js
 import Koa from 'koa';
@@ -35,6 +37,7 @@ const logger = createLogger(/* options */);
 
 app.use(logger);
 ```
+
 #### Log from middleware
 ```js
 // Log something in context to a specific request to trace it back easily -
@@ -109,6 +112,32 @@ const logger = createLogger({
 });
 ```
 
+### Standalone
+```js
+import createLogger from 'concurrency-logger';
+
+const logger = createLogger(/* options */);
+
+(async () => {
+    const context = {
+        method: 'GET',
+        originalUrl: '/'
+    };
+
+    const next = async () => {
+        await new Promise(resolve => setTimeout(resolve, 100));
+
+        context.status = 200;
+    };
+
+    try {
+        await logger(context, next);
+    } catch (error) {
+        // Errors are passed through
+    }
+});
+```
+
 ## API
 | Option | Type | Default | Description | Example |
 | ---- | ---- | ------- | ----------- | ------- |