docs: Update and more general wording for "docker container"

[dklimpel]

Checklist

• [x] make test-all (UNIX) passes. CI will also test this
• [ ] unit and/or integration tests are included (if applicable)
• [x] documentation is changed or added (if applicable)

Description of change

Fixes: #931

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📚 Documentation preview 📚: https://goss--934.org.readthedocs.build/en/934/

[aelsabbahy]

Thank you for submitting this.

Couple of feedbacks on this:

1. Removing docker from kgoss and in a few other places makes sense. But this PR is a little aggressive and removes docker from everything. dgoss is a docker (and also podman) wrapper for goss, dcgoss is a docker-compose wrapper for Goss

2. CI is failing, not sure why yet.