_content/doc: remove mention of -installsuffix removal

We ended up reverting CL 415236 due to a Google-internal dependency,
but I didn't update the doc fix CL before it was submitted.

Updates golang/go#51225.

Change-Id: I36142e6ea3f15251c54a7c3a6ddb953f9c18775f
Reviewed-on: https://go-review.googlesource.com/c/website/+/420614
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

_content/doc/go1.19.html

@@ -252,12 +252,10 @@ as well as support for rendering them to HTML, Markdown, and text.
   that invoke the Go compiler directly will need to make sure they
   pass this flag as well.
 </p>
-<p><!-- CL 415235 --><!-- CL 415236 -->
+<p><!-- CL 415235 -->
   The Go compiler no longer accepts the <code>-importmap</code>
-  or <code>-installsuffix</code> flags. Build systems that invoke the
-  Go compiler directly must use the <code>-importcfg</code> flag
-  instead. (The <code>go</code> command's <code>-installsuffix</code>
-  build flag is still supported and unaffected by this change.)
+  flag. Build systems that invoke the Go compiler directly must use
+  the <code>-importcfg</code> flag instead.
 </p>
 
 <h2 id="assembler">Assembler</h2>