Set default CONF_TYPE build arg in Dockerfile and add README

[sehlceris]

Hi there, thanks for creating this repo. It was very helpful to me.

I had some issues building the Dockerfile and had to figure out that I needed to set a build arg. I set one as default. I also added a short readme so that a user can more easily deploy it on their Coolify.

I am making this PR just in case you'd like to add this to your repo. Thanks!

[sehlceris]

Oh yeah, and right after this, I figured out I could just run nginx-proxy-manager inside coolify:

- create a new project/resource named nginx-proxy-manager
- docker image: jc21/nginx-proxy-manager | tag: latest
- domains: https://yourservice.yourdomain.com,https://nginx-proxy-manager.yourdomain.com:81
- note: the :81 is important since that will hit nginx-proxy-manager's admin port
- make sure your DNS for all those domains is pointed to your Coolify server
- add storage: name: "data" | destination path: "/data"
- add storage: name: "letsencrypt" | destination path: "/etc/letsencrypt"
- deploy
- visit https://nginx-proxy-manager.yourdomain.com (do not add any port afterward)
- default login is admin@example.com / changeme
- go to hosts tab -> proxy hosts
- add a proxy host
- domain names: yourservice.yourdomain.com
- scheme: http (coolify will take care of https, so nginx proxy manager is out of that chain)
- forward hostname/ip/port: whatever you want to proxy pass to, e.g. 192.168.1.21:8123
- enable websockets/block common exploits if you wish
- save. done.

references: https://nginxproxymanager.com/guide/

[andreitere]

Thanks a lot for the PR. it makes sense. I also tried npm first but I cannot remember, tbf, why i didn't go that way :D