New documentation on Docker method of running Snipe-IT. New environment

variables available to customize how Snipe-IT ought to work under
Docker. Locale, timezone, and custom-URL support. Documentation pushes
users to move more towards 'env-files' rather than environment variables.

Fixes #1020

docker/app.php

@@ -14,6 +14,10 @@ return array(
     */
 
     'debug' => false,
+    
+    'timezone' => isset($_ENV['SNIPEIT_TIMEZONE']) ? $_ENV['SNIPEIT_TIMEZONE'] : 'UTC',
+    'locale' => isset($_ENV['SNIPEIT_LOCALE']) ? $_ENV['SNIPEIT_LOCALE'] : 'en',
+
 
     /*
     |--------------------------------------------------------------------------