ipv4: drop package name prefix from identifiers in docs for consistency

Change-Id: I00b3297b88142ddb3c0cd08391171ebb6e731550
Reviewed-on: https://go-review.googlesource.com/34751
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

ipv4/doc.go

@@ -23,8 +23,8 @@
 // net.UDPConn and net.IPConn which are created as network connections
 // that use the IPv4 transport.  When a single TCP connection carrying
 // a data flow of multiple packets needs to indicate the flow is
-// important, ipv4.Conn is used to set the type-of-service field on
-// the IPv4 header for each packet.
+// important, Conn is used to set the type-of-service field on the
+// IPv4 header for each packet.
 //
 //	ln, err := net.Listen("tcp4", "0.0.0.0:1024")
 //	if err != nil {
@@ -96,8 +96,8 @@
 // The application might set per packet control message transmissions
 // between the protocol stack within the kernel.  When the application
 // needs a destination address on an incoming packet,
-// SetControlMessage of ipv4.PacketConn is used to enable control
-// message transmissions.
+// SetControlMessage of PacketConn is used to enable control message
+// transmissions.
 //
 //	if err := p.SetControlMessage(ipv4.FlagDst, true); err != nil {
 //		// error handling

ipv4/packet.go

@@ -64,7 +64,7 @@ func slicePacket(b []byte) (h, p []byte, err error) {
 //
 // The IPv4 header h must contain appropriate fields that include:
 //
-//	Version       = ipv4.Version
+//	Version       = <must be specified>
 //	Len           = <must be specified>
 //	TOS           = <must be specified>
 //	TotalLen      = <must be specified>