Use overflow: auto for description

Previously it sets overflow: scroll, so there's an unnecessary
horizontal scroll.
overflow: auto only shows scrollbar when it overflows

src/components/attachment/attachment.scss

@@ -37,7 +37,7 @@
       white-space: pre-line;
       word-break: break-word;
       text-overflow: ellipsis;
-      overflow: scroll;
+      overflow: auto;
     }
 
     &.-static {