Diagram: rebase-update-branch: clarify label; begin animation on-click
Diagram: rebase-update-branch: clarify label; begin animation on-click

- Add begin-on-click action to SVG image (start with rebase-update-branch).
- Adjust text label to clarify which action it is related to

emmajane/rebasing-workflow,gitforteams/rebasing-workflow,emmajane/rebasing-workflow,gitforteams/rebasing-workflow