bn256: add missing symbols in comment

Change-Id: Ibd48a070bd8ce35ef5795a8b73bc4ecac43a993e
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/611735
Run-TryBot: shuang cui <imcusg@gmail.com>
Commit-Queue: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>

Author: cuishuang

bn256/gfp12.go

@@ -5,7 +5,7 @@
 package bn256
 
 // For details of the algorithms used, see "Multiplication and Squaring on
-// Pairing-Friendly Fields, Devegili et al.
+// Pairing-Friendly Fields", Devegili et al.
 // http://eprint.iacr.org/2006/471.pdf.
 
 import (

bn256/gfp2.go

@@ -5,7 +5,7 @@
 package bn256
 
 // For details of the algorithms used, see "Multiplication and Squaring on
-// Pairing-Friendly Fields, Devegili et al.
+// Pairing-Friendly Fields", Devegili et al.
 // http://eprint.iacr.org/2006/471.pdf.
 
 import (

bn256/gfp6.go

@@ -5,7 +5,7 @@
 package bn256
 
 // For details of the algorithms used, see "Multiplication and Squaring on
-// Pairing-Friendly Fields, Devegili et al.
+// Pairing-Friendly Fields", Devegili et al.
 // http://eprint.iacr.org/2006/471.pdf.
 
 import (