Add date after updating

What does this Merge Request do?

When updating the GDK, I'd like to know when it finished so I have a good awareness of if I need to do it again.

This MR adds a timestamp after running gdk update.

Also, fixes a small typo.

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.