Splitting NF reqt from VES spec

Splitting NF reqt from VES spec

- Moved content in VES Event Listener spec that was specific
  to defining NF behavior to Monitoring requirements
- Expanded requirements regarding protocol selection
- Provided additional guidance for VES client configuration
- Reorganized sections of Event Listener for a more logical flow
- Fixed various small formatting issues in VES 7.2 spec

Issue-ID: VNFRQTS-813
Signed-off-by: Lovett, Trevor <trevor.lovett@att.com>
Change-Id: I4ca6fa4d846465c90520f8ebb133a1301d3509cf
Signed-off-by: Lovett, Trevor <trevor.lovett@att.com>