doc: add and fix System Error properties

[darai0512]

Checklist

• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

doc

Description of change

In System Errors properties of Errors API, error.path, error.address and error.port are not described although being also represented as augmented Error objects with added properties by the following code.

properties	link
address, port	https://github.com/nodejs/node/blob/v6.x-staging/lib/util.js#L1030-L1051
path	https://github.com/nodejs/node/blob/master/lib/child_process.js#L526

// examples
// with `path` property
$node -e "require('fs').readFile('a file that does not exist', (err, data) => { console.error(err); });"
{ Error: ENOENT: no such file or directory, open 'a file that does not exist'
    at Error (native)
  errno: -2,
  code: 'ENOENT',
  syscall: 'open',
  path: 'a file that does not exist' }

// with `address` and `port` property
$node -e "require('net').connect({port: 100}).on('error', (err) => { console.error(err); });"
{ Error: connect ECONNREFUSED 127.0.0.1:100
    at Object.exports._errnoException (util.js:1022:11)
    at exports._exceptionWithHostPort (util.js:1045:20)
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1087:14)
  code: 'ECONNREFUSED',
  errno: 'ECONNREFUSED',
  syscall: 'connect',
  address: '127.0.0.1',
  port: 100 }

// with `address` property (without `port` property)
$node -e "require('net').connect({host: 'localhost'}).on('error', (err) => { console.error(err); });"
{ Error: connect EADDRNOTAVAIL 127.0.0.1 - Local (0.0.0.0:54881)
    at Object.exports._errnoException (util.js:1022:11)
    at exports._exceptionWithHostPort (util.js:1045:20)
    at connect (net.js:881:16)
    at net.js:1010:7
    at GetAddrInfoReqWrap.asyncCallback [as callback] (dns.js:62:16)
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:81:10)
  code: 'EADDRNOTAVAIL',
  errno: 'EADDRNOTAVAIL',
  syscall: 'connect',
  address: '127.0.0.1' }

Also, error.errno doesn't always return a number like the above examples.
Please check the following code.

https://github.com/nodejs/node/blob/v6.x-staging/lib/util.js#L1024