doc/go1.19: remove TODO about LimitedReader

Rolled back in CL 410133.

For #51115.

Change-Id: I009c557acf98a98a9e5648fa82d998d41974ae60
Reviewed-on: https://go-review.googlesource.com/c/go/+/410357
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

Author: rsc

doc/go1.19.html

@@ -282,10 +282,6 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
 
 <dl id="io"><dt><a href="/pkg/io/">io</a></dt>
   <dd>
-    <p><!-- CL 396215 -->
-      TODO: <a href="https://go.dev/cl/396215">https://go.dev/cl/396215</a>: add an Err field to LimitedReader
-    </p>
-
     <p><!-- CL 400236 -->
       TODO: <a href="https://go.dev/cl/400236">https://go.dev/cl/400236</a>: NopCloser forward WriterTo implementations if the reader supports it
     </p>