Enhance event registration system:

- Update Google Sheets integration to support optional tab names.
- Add functionality to fetch and display public participants.
- Revise event configuration in YAML for clarity and consistency.
- Improve form layout with additional fields for contact information and meal preferences.
- Create a new home page template for event selection.
- Update success page to link back to the participants list.

templates/success.html

@@ -13,7 +13,10 @@
             <p class="lead">Je inschrijving voor <strong>{{ event.title }}</strong> is ontvangen.</p>
             <p>De gegevens zijn opgeslagen.</p>
             <hr>
-            <a href="https://docs.google.com/spreadsheets/d/{{ event.sheet_id }}" target="_blank" class="btn btn-outline-success">Bekijk deelnemers (Google Sheets)</a>
+            <!-- Link back to the form page, scrolled down to the list -->
+            <a href="/{{ slug }}#deelnemers" class="btn btn-primary">Bekijk deelnemerslijst</a>
+            <br><br>
+            <a href="/" class="btn btn-link text-muted">Terug naar overzicht</a>
         </div>
     </div>
 </body>