The pmm-server docker image does not work at all

Hi,

To begin with, version 1.x is published under the latest tag, if we follow the v2 doc then we are using the wrong version.

By following the documentation always, with everything by default, nothing starts.

Supervisor does not start because the `/var/run/supervisor` folder does not exist, I have to do a` mkdir /var/run/supervisor`.

I restart everything with `/opt/entrypoint.sh`.

And there I see that all the following services do not start:

```

nginx (exit status 1; not expected)
clickhouse (exit status 70; not expected)
cron (exit status 1; not expected)
qan-api2 (exit status 1; not expected)
pmm-agent (exit status 2; expected)

```

For nginx the `/var/cache/nginx/` folder is missing and the command `mkdir /var/cache/nginx/` fixes its case.

Here is my DEBUG log after that: https://pastebin.com/QxHBGTDM