Custom nginx config support

To adjust nginx config to an admins needs it would be nice to be able to include some custom nginx config (changes). For example to enable redirect support (80 > 443). Currently this can be done by editing the /etc/nginx files by hand but changes will be lost when the container is restarted. In order to preserve these changes accross container restarts it would suffice to move /etc/nginx/conf.d to /srv/nginx/conf.d.

Another possibility would be to add support in pmm-managed for custom nginx config (changes). Relates to https://jira.percona.com/browse/PMM-4996

See also forum