Add temporary link to subscription export instructions

src/invidious/views/data_control.ecr

@@ -14,7 +14,7 @@
 
             <div class="pure-control-group">
                 <label for="import_youtube">
-                    <a rel="noopener" target="_blank" href="https://support.google.com/youtube/answer/6224202?hl=en">
+                    <a rel="noopener" target="_blank" href="https://github.com/schwukas/invidious/wiki/Export-YouTube-subscriptions">
                         <%= translate(locale, "Import YouTube subscriptions") %>
                     </a>
                 </label>