Update Pipeline examples

[MarkEWaite]

Update Pipeline examples

Clarify the phrasing of several items and simplify the Pipeline examples by using modern syntax for the checkout scm examples.

Testing done

Confirmed that the examples work with Jenkins 2.492.2 and the most recent release of the git parameter plugin.

Will confirm that the formatting appears as expected after the pull request is created.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue