feat: add file upload pattern

index.html

@@ -51,6 +51,7 @@
         <li><a href="./patterns/content-cards-group.html">Content Cards Group</a></li>
         <li><a href="./patterns/card-gruppe-mit-tastennavigation.html">Card Gruppe mit Tastennavigation</a></li>
         <li><a href="./patterns/formular-mit-abschnitten.html">Formular mit Abschnitten</a></li>
+        <li><a href="./patterns/file-upload.html">Datei-Upload</a></li>
         <li><a href="./patterns/multiselektions-pulldown.html">Multiselektions-Pulldown</a></li>
         <li><a href="./patterns/text-layouts.html">Text Layouts</a></li>
         <li><a href="./patterns/delete-confirmation-overlay.html">Overlay Card</a></li>