Put our link to all mails and sync the formatting

src/mail_templates/certificate_renewal_error.ejs

@@ -1,13 +1,18 @@
 <%if (format === 'text') { %>
 
-Dear Cloudron Team,
-<%= domain %> was not renewed.
+Dear Cloudron Admin,
+
+the certificate for <%= domain %> could not be renewed.
+
+-------------------------------------
 
 <%- message %>
 
-Thank you,
-Your Cloudron
+-------------------------------------
+
+
+Powered by https://cloudron.io
+
 <% } else { %>
 
 <% } %>
-