Update various docs

Author: tamird

goid_go1.4.s

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Assembly to get into package runtime without using exported symbols.
-// See http://tip.golang.org/misc/cgo/test/backdoor/thunk.s.
+// See https://github.com/golang/go/blob/release-branch.go1.4/misc/cgo/test/backdoor/thunk.s
 
 // +build amd64 amd64p32 arm 386
 // +build go1.4,!go1.5

goid_go1.5.go

@@ -4,7 +4,8 @@ package goid
 
 import "unsafe"
 
-// Just enough of the structs from runtime2.go to get the offset to goid.
+// Just enough of the structs from runtime/runtime2.go to get the offset to goid.
+// See https://github.com/golang/go/blob/release-branch.go1.5/src/runtime/runtime2.go
 
 type stack struct {
 	lo uintptr

goid_go1.5plus.s

@@ -4,7 +4,7 @@
 // +build go1.5
 
 #include "textflag.h"
-	
+
 // func getg() uintptr
 TEXT ·getg(SB),NOSPLIT,$0-8
 	MOVQ (TLS), BX

goid_go1.6plus.go

@@ -5,6 +5,7 @@ package goid
 import "unsafe"
 
 // Just enough of the structs from runtime/runtime2.go to get the offset to goid.
+// See https://github.com/golang/go/blob/release-branch.go1.6/src/runtime/runtime2.go
 
 type stack struct {
 	lo uintptr
@@ -43,7 +44,7 @@ type g struct {
 }
 
 // Backdoor access to runtime·getg().
-func getg() uintptr // in goid_go1.5plus.s
+func getg() uintptr // in goid_go1.5plus{,_arm}.s
 
 func Get() int64 {
 	gg := (*g)(unsafe.Pointer(getg()))