make a note about how to use the docker containers in podman and galaxy

[exaexa]

...also slightly generalizing the container contents.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (bf57be9) 79.25% compared to head (23c522b) 79.25%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #83 +/- ## ======================================= Coverage 79.25% 79.25% ======================================= Files 20 20 Lines 617 617 ======================================= Hits 489 489 Misses 128 128 ```

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