adding support to use custom /etc/exports file

[mynktl]

Hello,

Thanks for creating this wonderful project.

We are using docker image from https://github.com/sjiveson/nfs-server-alpine in our project https://github.com/openebs/dynamic-nfs-provisioner. To extend the functionality, We need to provide a custom /etc/export file to nfsd.sh. Can we add support to use export config through env?

As of now, as a workaround, we are creating our docker image with a modified file to pass custom export configuration. Reference PR: openebs-archive/dynamic-nfs-provisioner#22.

We are also planning to add multi-arch support to the Docker file. Wanted to check your interest in accepting the PRs for the same.

Thanks!

[colearendt]

Whew, time flies. In any case, I wanted to share that I explored something similar in #23 a while back. I'll take a pass on fixing up the merge conflicts here before long