Add the blog link in the header and footer

customize.dist/src/fragments/footer.html

@@ -22,6 +22,7 @@
                     <div class="col">
                         <ul class="list-unstyled">
                             <li class="title" data-localization="footer_aboutUs"><li>
+                            <li><a href="https://blog.cryptpad.fr" target="_blank" data-localization="blog" rel="noopener noreferrer">Blog</a></li>
                             <li><a href="https://labs.xwiki.com" target="_blank" rel="noopener noreferrer">XWiki Labs</a></li>
                             <li><a href="http://www.xwiki.com" target="_blank" rel="noopener noreferrer">XWiki SAS</a></li>
                             <li><a href="https://www.open-paas.org/" target="_blank" rel="noopener noreferrer">OpenPaaS</a></li>