oauth2: fix lint errors

Change-Id: I9cc4c61767be5e6eda189468430e9a89fe2f3796
diff --git a/jws/jws.go b/jws/jws.go
index d12d033..61cbfc5 100644
--- a/jws/jws.go
+++ b/jws/jws.go
@@ -20,7 +20,7 @@
 	"time"
 )
 
-// The JWT claim set contains information about the JWT including the
+// ClaimSet contains information about the JWT signature including the
 // permissions being requested (scopes), the target of the token, the issuer,
 // the time the token was issued, and the lifetime of the token.
 type ClaimSet struct {
diff --git a/transport.go b/transport.go
index 5062bd2..0192aac 100644
--- a/transport.go
+++ b/transport.go
@@ -19,16 +19,16 @@
 // the requests to access protected resources on the OAuth 2.0
 // provider's backend.
 type Token struct {
-	// A token that authorizes and authenticates the requests.
+	// AccessToken is the token that authorizes and authenticates the requests.
 	AccessToken string `json:"access_token"`
 
-	// Identifies the type of token returned.
+	// TokenType identifies the type of token returned.
 	TokenType string `json:"token_type,omitempty"`
 
-	// A token that may be used to obtain a new access token.
+	// RefreshToken is a token that may be used to obtain a new access token.
 	RefreshToken string `json:"refresh_token,omitempty"`
 
-	// The remaining lifetime of the access token.
+	// Expiry is the expiration datetime of the access token.
 	Expiry time.Time `json:"expiry,omitempty"`
 
 	// raw optionally contains extra metadata from the server