[CDash] Using the Docker images is problematic

[Cristian Morales Vega]

It's nice to have CDash Docker images. But

a) I don't think anywhere in https://www.cdash.org/ the Docker images
availability is mentioned
b) https://github.com/Kitware/cdash-docker seems badly outdated (e.g.
apt-get install libpng12-dev fails, with libpng-dev works OK)
c) The hash from here
(https://github.com/Kitware/cdash-docker/blob/master/Dockerfile#L16)
seems outdated

Still, after fixing 'a' and 'c', I can easily get a CDash instance up
and running. Which is nice.

But if instead of using the Dockerfile from that repository I change
https://github.com/Kitware/cdash-docker/blob/master/docker-compose.yml#L4
from "kitware/cdash-docker" to "kitware/cdash" or
"kitware/cdash:v2.6.0", so the version from Docker Hub
(https://hub.docker.com/r/kitware/cdash) is used, my CDash
installation fails to work because the MySQL doesn't seem to have the
correct tables in place (e.g. I can't login because there is no
"cdash.user" table).

I know zero about PHP or MySQL. And not a lot more about Docker. So I
may be doing something silly. But it seems to me that with just a
little bit more effort in documentation/maintainership this could be
used even by somebody like me... which would hopefully make CDash more
popular by increasing the amount of people actually able to use it.