Improves README and add install doc page

Shows how to install as a composer dependency

example.index.php

@@ -0,0 +1,11 @@
+<?php
+// template file for creating your own Minify endpoint
+
+// remove this
+die('disabled');
+
+// adjust this path as necessary
+require __DIR__ . '/../vendor/autoload.php';
+
+$app = new \Minify\App(__DIR__);
+$app->runServer();