doc: More accurate description for ports occupied

1. Output port info need '--verbose' option enabled
2. Update sample lines for the ports info
3. Ports 5000~5003 may be occupied by other programs
4. Fix starting port number to 5000
5. Add -k and --verbose option in command for consistency

Issue-Id: SCM-4502
Signed-off-by: Robbie Cao <robbie.cao@arm.com>
Change-Id: I9d6bbbd498b13077c29ae04e133bcb77670bb4e4