Update PHPDocs and add missing required param visibility to model project in createSnippet method

Author: mirko-jtl

lib/Gitlab/Api/Snippets.php

@@ -26,6 +26,7 @@ public function show($project_id, $snippet_id)
      * @param string $title
      * @param string $filename
      * @param string $code
+     * @param $visibility
      * @return mixed
      */
     public function create($project_id, $title, $filename, $code, $visibility)

lib/Gitlab/Model/Project.php

@@ -937,11 +937,12 @@ public function snippets()
      * @param string $title
      * @param string $filename
      * @param string $code
+     * @param $visibility
      * @return Snippet
      */
-    public function createSnippet($title, $filename, $code)
+    public function createSnippet($title, $filename, $code, $visibility)
     {
-        $data = $this->client->snippets()->create($this->id, $title, $filename, $code);
+        $data = $this->client->snippets()->create($this->id, $title, $filename, $code, $visibility);
 
         return Snippet::fromArray($this->getClient(), $this, $data);
     }