add basic documentation

readme.md

@@ -3,3 +3,73 @@
 [![Travis Build](http://img.shields.io/travis/maximilianschmitt/sleepqueue.svg?style=flat)](https://travis-ci.org/maximilianschmitt/sleepqueue) [![Code Coverage](https://img.shields.io/coveralls/maximilianschmitt/sleepqueue.svg)](https://coveralls.io/r/maximilianschmitt/sleepqueue) [![npm](https://img.shields.io/npm/dm/sleepqueue.svg)](https://www.npmjs.com/package/sleepqueue)
 
 A promise-based queue that sleeps between callbacks.
+
+## Installation
+
+```
+$ npm i sleepqueue -S
+```
+
+## Usage
+
+### General
+
+```js
+var sleepqueue = require('./sleepqueue');
+
+// create a queue with an interval of 1 second
+var queue = sleepqueue({ interval: 1000 });
+
+// `push` pushes to the end of the queue
+queue.push(print('My name is'));
+queue.push(print('My name is'));
+queue.push(print('My name is'));
+queue.push(print('Slim Shady'));
+//
+// `unshift` pushes to the start of the queue
+queue.unshift(print('Hi'));
+
+// just a helper function
+function print(what) {
+  return function() {
+    console.log(what);
+  };
+}
+```
+
+Output:
+
+```
+Hi
+# (wait 1 second)
+My name is
+# (wait 1 second)
+My name is
+# (wait 1 second)
+My name is
+# (wait 1 second)
+Slim Shady
+```
+
+### Errors
+
+Uncaught errors and rejected promises will stop the queue and emit an error event.
+
+```js
+queue.push(print('Hello'));
+queue.push(function() {
+  throw 'I stopped the queue';
+});
+queue.push(print('Bye'));
+
+queue.on('error', function(err) {
+  console.log('Error: ' + err);
+});
+```
+
+Output:
+
+```
+Hello
+Error: I stopped the queue
+```