Add README

Author: legionth

README.md

@@ -0,0 +1,85 @@
+# ProgressbarStream
+
+An event-driven progressbar stream that can be added to other streams
+to show its current progress.
+
+**Table of Contents**
+ * [Usage](#usage)
+   * [data-Event](#data-event)
+   * [currentValue-Event](#currentvalue-event)
+   * [maximumValue-Event](#maximumvalue-event)
+ * [Installation](#installation)
+ 
+## Usage
+
+This stream can be integrate like any other
+[ReactPHP Stream](https://github.com/reactphp/stream/)
+
+```php
+$loop = Factory::create();
+
+$progressBarStream = new ProgressbarStream();
+
+$input = new React\Stream\WritableResourceStream(STDOUT, $loop);
+$output = new React\Stream\ReadableResourceStream(STDIN, $loop);
+
+$output->pipe($progressBarStream);
+
+$progressBarStream->on('error', function ($errorMessage) {
+    echo $errorMessage;
+});
+
+$progressBarStream->on('data', function ($progressBarString) use ($input) {
+    $input->write($progressBarString . PHP_EOL);
+});
+
+$loop->addPeriodicTimer(1, function () use ($output) {
+    $output->emit('data', array(1));
+});
+
+$loop->addPeriodicTimer(3, function () use ($output) {
+    $output->emit('data', array(10));
+});
+
+$loop->run();
+```
+
+This example will update the progressbar every 1 second by 1 unit/percent and
+every 3 seconds by 10 units/percent.
+This example can be found in the [examples folder](/examples).
+
+The progressbar stream will never overflow the maximum value.
+The stream will end if the current value reaches or goes beyond the maximum
+value.
+
+### data-Event
+
+The `data` event contains the visualization of the progress bar.
+The data emitted by this event is a string.
+This event will be emitted if the progressbar is updated.
+
+### currentValue-Event
+
+The `currentValue` event contains the integer value of the current progressbar.
+This event will be emitted if the progressbar is updated.
+
+### maximumValue-Event
+
+The `maximumValue` event contains the integer value of the maximum reachable value
+of the progressbar.
+This event will be emitted if the progressbar is updated.
+
+### Customize
+
+The constructor
+
+## Installation
+
+The recommended way to install this library is [through Composer](https://getcomposer.org).
+[New to Composer?](https://getcomposer.org/doc/00-intro.md)
+
+This will install the latest supported version:
+
+```bash
+$ composer require legionth/progressbar:^1.0
+```