Nudge users to turn on discoverable when viewing the empty list of collections they are in (#39029)

Co-authored-by: diondiondion <mail@diondiondion.com>

app/javascript/mastodon/components/empty_state/empty_state.module.scss

@@ -35,6 +35,10 @@
     color: var(--color-text-secondary);
     text-wrap: pretty;
   }
+
+  a {
+    color: var(--color-text-status-links);
+  }
 }
 
 [data-color-scheme='dark'] .defaultImage {