warn about hmac key deadline

src/invidious/views/template.ecr

@@ -111,6 +111,14 @@
                 </div>
             <% end %>
 
+            <% if env.get? "user" %>
+                <% if !HMAC_KEY_CONFIGURED && CONFIG.admins.includes? env.get("user").as(Invidious::User).email %>
+                <div class="h-box">
+                        <h3><p>Message for admin: please configure hmac_key, <a href="https://github.com/iv-org/invidious/issues/3854">see more here</a>.</p></h3>
+                    </div>
+                <% end %>
+            <% end %>
+
             <%= content %>
 
             <footer>