[release-branch.go1.12] doc: document Go 1.12.4 and Go 1.11.9

Updates #31293

Change-Id: I3d72f732be7b28059310ea6fc134c3bfac81492d
Reviewed-on: https://go-review.googlesource.com/c/go/+/171578Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
(cherry picked from commit ab2a0803)
Reviewed-on: https://go-review.googlesource.com/c/go/+/171766Reviewed-by: Bryan C. Mills <bcmills@google.com>

doc/devel/release.html

@@ -49,7 +49,13 @@ command, the runtime, and the <code>doc</code>, <code>net</code>,
 </p>
 
 <p>
-go1.12.3 (released 2019/04/08) fixes an issue where using the prebuilt binary
+go1.12.3 (released 2019/04/08) was accidentally released without its
+intended fix. It is identical to go1.12.2, except for its version
+number. The intended fix is in go1.12.4.
+</p>
+
+<p>
+go1.12.4 (released 2019/04/11) fixes an issue where using the prebuilt binary
 releases on older versions of GNU/Linux
 <a href="https://golang.org/issues/31293">led to failures</a>
 when linking programs that used cgo.
@@ -122,7 +128,13 @@ go1.11.7 (released 2019/04/05) includes fixes to the runtime and the
 </p>
 
 <p>
-go1.11.8 (released 2019/04/08) fixes an issue where using the prebuilt binary
+go1.11.8 (released 2019/04/08) was accidentally released without its
+intended fix. It is identical to go1.11.7, except for its version
+number. The intended fix is in go1.11.9.
+</p>
+
+<p>
+go1.11.9 (released 2019/04/11) fixes an issue where using the prebuilt binary
 releases on older versions of GNU/Linux
 <a href="https://golang.org/issues/31293">led to failures</a>
 when linking programs that used cgo.