Improve documentation

Author: tylers-username

README.md

@@ -2,3 +2,43 @@
 
 Magento 2 Downloader for Commerce & Open Source
 
+Download mage2me
+----------------
+
+```bash
+curl -L https://github.com/improper/mage2me/releases/latest/download/mage2me --output mage2me
+chmod u+x ./mage2me
+./mage2me --version
+```
+
+Download & Install Magento
+--------------------------
+
+Some of the options shown below are indeed optional. Checkout `./mage2me --help` for more info. 
+
+```bash
+./mage2me output-directory \
+    --mage-edition "Open Source" \
+    --mage-version "2.3.5" \
+    --github-token $GITHUB_TOKEN \
+    --mage-access-key-public $MAGENTO_PUBLIC_KEY \
+    --mage-access-key-private $MAGENTO_PRIVATE_KEY
+
+cd magento-directory
+composer install
+```
+
+List Download Options
+---------------------
+
+```bash
+./mage2me --help
+```
+
+
+List Global Options
+-------------------
+
+```bash
+./mage2me list
+```

bin/mage2me.php

@@ -7,5 +7,6 @@
 
 $application = new Application('mage2me', 'v1.0.0');
 $application->add(new DownloadCommand());
+$application->setDefaultCommand('download');
 $application->run();
 

src/CommandTraits/MagentoVersionCommandTraits.php

@@ -35,7 +35,7 @@ public function addOptionMageVersion()
             $this->keyMageVersion(),
             null,
             InputOption::VALUE_OPTIONAL,
-            'Magento Edition',
+            'Magento Edition. [2.1, 2.2, 2.3.5, 2.4-develop, ...]',
             '2.3.5'
         );
     }