[2.0] working with Docker images

[timhallinflux]

Folks picking up the Docker images are looking for additional guidance about how to consume the image and effectively work with it.

1. volume mounts -- folks want to persist their data outside the docker image. Looks like everything resides within /root/.influxdbv2.
2. creating a config file -- assuming the volume mounts are made, should they be able to drop a config.toml into the same directory and have the influxd process pick that up and read it. Let's show an example.

[timhallinflux]

Another request for help outlined here: https://www.orpiske.net/2020/12/using-go-and-influxdb-to-find-the-best-time-to-go-the-gym/

[danxmoran]

@kelseiv I took a 1st stab at docs for the new DockerHub build, it's in review at docker-library/docs#1871

[pierwill]

Checking in on this.

Wow, @danxmoran! A lot of great info in that PR! I've got the basics working with the -v flag in Docker. First thing I'll do to address @timhallinflux's item 1 above is to add a minimal example of persisting data outside the Docker contain in the Docker section of https://docs.influxdata.com/influxdb/v2.0/get-started/.

Next (item 2), we can make sure we have easy access to instructions for picking up a config file from the mounted volume. That might be a minimal example plus a link to docker-library.