unify on workflow engine terminology

[christinaausley]

Description

Closes https://github.com/camunda/documentation-team/issues/52 -- standardizes on "workflow engine" rather than process automation engine, BPM engine, and BPMN engine.

When should this change go live?

• This is a bug fix, security concern, or something that needs urgent release support. (add bug or support label)
• This is already available but undocumented and should be released within a week. (add available & undocumented label)
• This is on a specific schedule and the assignee will coordinate a release with the DevEx team. (create draft PR and/or add hold label)
• This is part of a scheduled alpha or minor. (add alpha or minor label)
• There is no urgency with this change (add low prio label)

PR Checklist

• My changes are for an upcoming minor release and:
  • are in the /docs directory (version 8.8).
  • are in the /versioned_docs/version-8.7/ directory (version 8.7).
• My changes are for an already released minor and are in a /versioned_docs directory.

• I added a DRI, team, or delegate as a reviewer for technical accuracy and grammar/style:
  • Engineering team review
  • Technical writer review via @camunda/tech-writers unless working with an embedded writer.

[akeller]

What about "business process execution engine"? I noticed it on the glossary page, should this be adjusted to? If not, how are they different?

I'm also not sure how often we use the other terms. Should those be added as glossary terms pointing to workflow engine as synonyms?

[christinaausley]

@akeller We use that in two instances:

in manual-tasks.md:

Manual tasks are part of human task orchestration, but differ from user tasks which define an actionable task assisted by a business process execution engine or software application.

in user-tasks.md:

A user task is used to model work that needs to be done by a human and is assisted by a business process execution engine or software application. This differs from manual tasks, which are not assisted by external tooling.

These got looped in when we did the user task/manual task differentiation work. I think it can be replaced with "workflow engine" in both places and removed from the glossary.

[akeller]

👍 non-blocking feedback to remove Camunda and Camunda 8 in the same sentence.

[akeller]

Suggested change

	A workflow engine is an essential part of any process automation tool. We call it an “engine” because it drives business processes from start to finish, no matter how complex the process and decision logic need to be. At Camunda, [Zeebe](/components/zeebe/zeebe-overview.md) is the workflow engine powering Camunda 8.
	A workflow engine is an essential part of any process automation tool. We call it an “engine” because it drives business processes from start to finish, no matter how complex the process and decision logic need to be. [Zeebe](/components/zeebe/zeebe-overview.md) is the workflow engine powering Camunda 8.

Just felt a little redundant. If this wasn't docs, I would rewrite the first two sentences with a ; but I think it's fine.