Improved docs about vendor name protection (#962)

issue #163

src/Packagist/WebBundle/Resources/views/About/about.html.twig

@@ -38,6 +38,7 @@ monolog/monolog-drupal-module
 // Acme is a company or person here, they can name their package with a common name (Email).
 // As long as it's in their own vendor namespace it does not conflict with anyone else.
 acme/email</code></pre>
+            <p>Vendor names on packagist are protected once a package with that name has been published. That means you can not publish packages with a vendor name that already exists on packagist without permission. To be able to publish packages for an already existing vendor name you need to be maintainer of at least one package within that vendor.</p>
             <p>Note that package names are case-insensitive, but it's encouraged to use a dash (-) as separator instead of CamelCased names.</p>
         </section>