net: update documentation for UnixConn, UnixListener and related stuff

Closes the API documentation gap between platforms.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8063044

src/pkg/net/unixsock.go

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Unix domain sockets
-
 package net
 
 // UnixAddr represents the address of a Unix domain socket end point.

src/pkg/net/unixsock_plan9.go

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Unix domain sockets stubs for Plan 9
-
 package net
 
 import (
@@ -133,9 +131,9 @@ func (l *UnixListener) File() (*os.File, error) {
 }
 
 // ListenUnixgram listens for incoming Unix datagram packets addressed
-// to the local address laddr.  The returned connection c's ReadFrom
-// and WriteTo methods can be used to receive and send packets with
-// per-packet addressing.  The network net must be "unixgram".
+// to the local address laddr.  The network net must be "unixgram".
+// The returned connection's ReadFrom and WriteTo methods can be used
+// to receive and send packets with per-packet addressing.
 func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
 	return nil, syscall.EPLAN9
 }

src/pkg/net/unixsock_posix.go

@@ -4,8 +4,6 @@
 
 // +build darwin freebsd linux netbsd openbsd windows
 
-// Unix domain sockets
-
 package net
 
 import (
@@ -344,9 +342,9 @@ func (l *UnixListener) SetDeadline(t time.Time) (err error) {
 func (l *UnixListener) File() (f *os.File, err error) { return l.fd.dup() }
 
 // ListenUnixgram listens for incoming Unix datagram packets addressed
-// to the local address laddr.  The returned connection c's ReadFrom
-// and WriteTo methods can be used to receive and send packets with
-// per-packet addressing.  The network net must be "unixgram".
+// to the local address laddr.  The network net must be "unixgram".
+// The returned connection's ReadFrom and WriteTo methods can be used
+// to receive and send packets with per-packet addressing.
 func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
 	switch net {
 	case "unixgram":