docs(example): fix multiple h1 warning in news template example

Author: Lausselloic

docs/4.0/examples/news-template/index.html

@@ -464,7 +464,7 @@ <h5 class="mb-0">
     </main>
 
     <footer class="o-footer" role="contentinfo">
-      <h1 class="sr-only">footer - site map & informations</h1>
+      <h2 class="sr-only">footer - site map & informations</h2>
       <div class="o-footer-top">
           <div class="container-fluid">
               <ul class="nav">