os: fix reference to nonexistent errors.Wrapper

Change-Id: I857d39486cbddbbee0c00fd45eb77f21488f4806
GitHub-Last-Rev: 1b500183cfebadffb4c183e56850bfb794a11703
GitHub-Pull-Request: golang/go#35399
Reviewed-on: https://go-review.googlesource.com/c/go/+/205602Reviewed-by: Jonathan Amsterdam <jba@google.com>

src/os/error.go

@@ -110,7 +110,7 @@ func IsTimeout(err error) bool {
 func underlyingErrorIs(err, target error) bool {
 	// Note that this function is not errors.Is:
 	// underlyingError only unwraps the specific error-wrapping types
-	// that it historically did, not all errors.Wrapper implementations.
+	// that it historically did, not all errors implementing Unwrap().
 	err = underlyingError(err)
 	if err == target {
 		return true