dl: add go1.18.9

Change-Id: I3d96d33e9c7d52e1849ec6efcf2c8e065634af62
Reviewed-on: https://go-review.googlesource.com/c/dl/+/455595
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Gopher Robot <gobot@golang.org>
Auto-Submit: Gopher Robot <gobot@golang.org>
Reviewed-by: Jenny Rakoczy <jenny@golang.org>

go1.18.9/main.go

diff --git a/go1.18.9/main.go b/go1.18.9/main.go
new file mode 100644
index 0000000..5f0cc5e
--- /dev/null
+++ b/go1.18.9/main.go
@@ -0,0 +1,24 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The go1.18.9 command runs the go command from Go 1.18.9.
+//
+// To install, run:
+//
+//	$ go install golang.org/dl/go1.18.9@latest
+//	$ go1.18.9 download
+//
+// And then use the go1.18.9 command as if it were your normal go
+// command.
+//
+// See the release notes at https://go.dev/doc/devel/release#go1.18.minor.
+//
+// File bugs at https://go.dev/issue/new.
+package main
+
+import "golang.org/dl/internal/version"
+
+func main() {
+	version.Run("go1.18.9")
+}