Define error pages

https://github.com/Reposoft/docker-svn/blob/v0.6.1/httpd/conf/rweb/load-fpm.conf#L10

for https://github.com/Reposoft/rweb/tree/master/repos-web/errors

Dynamic error pages is a quite bad idea, if errors are caused by httpd<->rweb issues. Therefore the docker build must generate static error pages for apache.