doc: fix typo in 1.20 release notes

Fix typo.

Change-Id: Id3a78ac5d8ea429ba1685889cd1661aaca8572c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/456238
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>

Author: thanm

doc/go1.20.html

@@ -308,7 +308,7 @@ <h2 id="runtime">Runtime</h2>
 <p><!-- https://go.dev/issue/51430 -->
   Go 1.20 adds a new <code>runtime/coverage</code> package
   containing APIs for writing coverage profile data at
-  runtime from a long-running and/or server programs that
+  runtime from long-running and/or server programs that
   do not terminate via <code>os.Exit()</code>.
 </p>