core/types: fix docs about protected Vs (#17436)

core/types/transaction.go

@@ -119,7 +119,7 @@ func isProtectedV(V *big.Int) bool {
 		v := V.Uint64()
 		return v != 27 && v != 28
 	}
-	// anything not 27 or 28 are considered unprotected
+	// anything not 27 or 28 is considered protected
 	return true
 }