update data/versions.yml and archive index page

Author: howardjohn

archive/archive/index.html

@@ -10,6 +10,9 @@
     <input type=hidden id=search-page-url value=/search>
     <input id=search-textbox class=form-control name=q type=search aria-label="Search this site">
     <button id=search-close title="Cancel search" type=reset aria-label="Cancel search"><svg class="icon"><use xlink:href="./img/icons.svg#cancel-x"/></svg></button></form></nav></header><div class=banner-container></div><main class="primary notoc"><div id=sidebar-container class="sidebar-container sidebar-offcanvas"></div><div class=article-container><h1>istio.io Archives</h1><p>Snapshots of the <a href=https://istio.io>istio.io</a> website for each release.</p><ul>
+        <li>
+            <a href=/v1.24>v1.24</a>
+        </li>
         <li>
             <a href=/v1.23>v1.23</a>
         </li>

data/versions.yml

@@ -1,5 +1,5 @@
 # The version of Istio currently documented in istio.io
-main: "1.24"
+main: "1.25"
 
 # The version of Istio currently documented in preliminary.istio.io
-preliminary: "1.25"
+preliminary: "1.26"