Allow certs for domains which are available

src/freedombone-sec

                 domain_found=1
             fi
         fi
+        if [ -f /etc/nginx/sites-available/${new_domain} ]; then
+            domain_found=1
+        fi
         if [ ! $domain_found ]; then
             dialog --title $"Create a new Let's Encrypt certificate" \
                    --msgbox $'Domain not found within /var/www' 6 40