Permission handling added

- Updated section 4. Security and privacy considerations
- Added interface TCPPermission (UDPPermission and TCPserverPermission remains but wants to get feedback before going further)
- Editorial corrections
https://github.com/sysapps/tcp-udp-sockets/issues/81
Yes, it seems reasonable to have something like <host-pattern> here. Maybe this should be related to CSP connect-src?