_content/doc/go1.18: remove draft notice

For golang/go#51683.
Fixes golang/go#47694.

Change-Id: I2d2842e78ba1c413b8171fd24f8fb18fa549c816
Reviewed-on: https://go-review.googlesource.com/c/website/+/390375
Trust: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: DO NOT USE <iant@google.com>

_content/doc/go1.18.html

@@ -14,13 +14,15 @@
   main ul li { margin: 0.5em 0; }
 </style>
 
-<h2 id="introduction">DRAFT RELEASE NOTES — Introduction to Go 1.18</h2>
+<h2 id="introduction">Introduction to Go 1.18</h2>
 
 <p>
-  <strong>
-    Go 1.18 is not yet released. These are work-in-progress
-    release notes. Go 1.18 is expected to be released in March 2022.
-  </strong>
+  The latest Go release, version 1.18,
+  is a significant release, including changes to the language,
+  implementation of the toolchain, runtime, and libraries.
+  Go 1.18 arrives seven months after <a href="/doc/go1.17">Go 1.17</a>.
+  As always, the release maintains the Go 1 <a href="/doc/go1compat">promise of compatibility</a>.
+  We expect almost all Go programs to continue to compile and run as before.
 </p>
 
 <h2 id="language">Changes to the language</h2>