doc/go1.15: mention new debug/pe constants

The constants were added in CL 222637.

For #37419

Change-Id: Iae662d677d31c44a7560399ef6771f520c1f7663
Reviewed-on: https://go-review.googlesource.com/c/go/+/236682
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/doc/go1.15.html b/doc/go1.15.html
index 0c345f2..a863b96 100644
--- a/doc/go1.15.html
+++ b/doc/go1.15.html
@@ -328,7 +328,10 @@
 <dl id="debug/pe"><dt><a href="/pkg/debug/pe/">debug/pe</a></dt>
   <dd>
     <p><!-- CL 222637 -->
-      TODO: <a href="https://golang.org/cl/222637">https://golang.org/cl/222637</a>: copy some consts from cmd/link/internal/ld
+      The package now defines the
+      <code>IMAGE_FILE</code>, <code>IMAGE_SUBSYSTEM</code>,
+      and <code>IMAGE_DLLCHARACTERISTICS</code> constants used by the
+      PE file format.
     </p>
   </dd>
 </dl><!-- debug/pe -->