v-m: scrape: Fix Nextcloud URL

Nextcloud uses a _client-side_ (Javascript) redirect to navigate the
browser to its `index.php`.  The page it serves with this redirect is
static and will often load successfully, even if there is a problem with
the application.  This causes the Blackbox exporter to record the site
as "up," even when it it definitely is not.  To avoid this, we can
scrape the `index.php` page explicitly, ensuring that the application is
loaded.

20125/config.yml

@@ -31,7 +31,7 @@ applications:
   - instance: homeassistant.pyrocufflink.blue
 
 - name: Nextcloud
-  url: &url https://nextcloud.pyrocufflink.net/
+  url: &url https://nextcloud.pyrocufflink.net/index.php
   icon:
     url: icons/nextcloud.png
   alerts: