add logout button to admin texts page

views/templates/texts.php

@@ -14,6 +14,7 @@
                 <a class="btn btn-secondary" href="/admin" id="back">
                     Back to Admin
                 </a>
+                <button id="logout" class="btn btn-danger">Logout</button>
             </div>
         </div>
     </header>
@@ -31,6 +32,7 @@
             </div>
         </form>
     </main>
+    <script src="/js/auth.js"></script>
     <script src="/js/texts.js"></script>
 </body>
 </html>