Fix multi rrd on app.rerun.io (#6972)

Author: jprochazk

web_viewer/index.html

@@ -340,7 +340,7 @@
           persist: Option<bool>,
         */
         const options = {
-          url: query.get("url"),
+          url: query.getAll("url"),
           manifest_url: query.get("manifest_url"),
           render_backend: query.get("renderer"),
           hide_welcome_screen: query.has("hide_welcome_screen"),