oauth2: fix docs for Config.DeviceAuth

Config.DeviceAccess should be Config.DeviceAuth when using GenerateVerifier() or S256ChallengeOption()

Change-Id: Ie21a808387f731d270ae54ea1705de3e786cad7f
GitHub-Last-Rev: 2d6b4fd736ce785cc1675b1963be165529b09b1f
GitHub-Pull-Request: golang/oauth2#763
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/636216
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Jorropo <jorropo.pgm@gmail.com>
Reviewed-by: Jorropo <jorropo.pgm@gmail.com>

pkce.go

diff --git a/pkce.go b/pkce.go
index 50593b6..6a95da9 100644
--- a/pkce.go
+++ b/pkce.go
@@ -21,7 +21,7 @@
 //
 // A fresh verifier should be generated for each authorization.
 // S256ChallengeOption(verifier) should then be passed to Config.AuthCodeURL
-// (or Config.DeviceAccess) and VerifierOption(verifier) to Config.Exchange
+// (or Config.DeviceAuth) and VerifierOption(verifier) to Config.Exchange
 // (or Config.DeviceAccessToken).
 func GenerateVerifier() string {
 	// "RECOMMENDED that the output of a suitable random number generator be
@@ -51,7 +51,7 @@
 }
 
 // S256ChallengeOption derives a PKCE code challenge derived from verifier with
-// method S256. It should be passed to Config.AuthCodeURL or Config.DeviceAccess
+// method S256. It should be passed to Config.AuthCodeURL or Config.DeviceAuth
 // only.
 func S256ChallengeOption(verifier string) AuthCodeOption {
 	return challengeOption{