Set the Gitea root URL to HTTPS

It fixes U2F security keys support, that was broken because the protocol
did not match

Fixes #182

site-cookbooks/kosmos_gitea/templates/default/app.ini.erb

@@ -8,7 +8,8 @@ DISABLE_SSH      = false
 SSH_PORT         = 22
 PROTOCOL = http
 DOMAIN = gitea.kosmos.org
-ROOT_URL = %(PROTOCOL)s://%(DOMAIN)s
+# Gitea is running behind an nginx reverse load balancer, use an HTTPS root URL
+ROOT_URL = https://%(DOMAIN)s
 # REDIRECT_OTHER_PORT = true
 # PORT_TO_REDIRECT = 3001
 # ENABLE_LETSENCRYPT = true