_content/doc/articles/race_detector: document linux/s390x support

Support for linux/s390x was added in Go 1.19.

Change-Id: I939601ad707da5d6a81ba85662b1ed37b0feccbb
GitHub-Last-Rev: 837e2a8c06ad5630ca8e7c63d812bceaf5860967
GitHub-Pull-Request: golang/website#262
Reviewed-on: https://go-review.googlesource.com/c/website/+/544477
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/_content/doc/articles/race_detector.html b/_content/doc/articles/race_detector.html
index 80f186c..069741f 100644
--- a/_content/doc/articles/race_detector.html
+++ b/_content/doc/articles/race_detector.html
@@ -417,9 +417,10 @@
   systems requires an installed C compiler.
   The race detector supports
   <code>linux/amd64</code>, <code>linux/ppc64le</code>,
-  <code>linux/arm64</code>, <code>freebsd/amd64</code>,
-  <code>netbsd/amd64</code>, <code>darwin/amd64</code>,
-  <code>darwin/arm64</code>, and <code>windows/amd64</code>.
+  <code>linux/arm64</code>, <code>linux/s390x</code>,
+  <code>freebsd/amd64</code>, <code>netbsd/amd64</code>,
+  <code>darwin/amd64</code>, <code>darwin/arm64</code>,
+  and <code>windows/amd64</code>.
 </p>
 
 <p>