Review vocabulary around workflows in the documentation
We should review the [introduction](https://freexian-team.pages.debian.net/debusine/explanation/concepts.html#workflows) and the [tutorial](https://freexian-team.pages.debian.net/debusine/tutorials/getting-started-with-debusine.html) (and maybe other pages) to try to try clarify the relationship between "Debusine Workflows" as in "Orchestration logic supported by Debusine as a software", "Workflow templates" as in "Configured workflows made available in a workspace" and "Workflows" as in "Running instance of a workflow".
We should come up with a proper terminology, and also proper verbs associated to each action:
* Going from "Debusine workflows" to a "Workflow template" could be named "Configuring a workflow"
* Going from "Workflow template" to a "Running workflow" could be named "Starting a workflow"
"Workflow template" is rather arcane, I wonder whether we should note aim to use "Configured workflows" in the documentation and user interface, and keep the WorkflowTemplate only for development.
(split off from #770, /cc @mbehrle)
issue