doc/go1.16: add link to reflect.StructTag

For #40700.

Change-Id: I67dd55b435304e428929c9a54b8881f9b78efdfb
Reviewed-on: https://go-review.googlesource.com/c/go/+/278392
Trust: Tobias Klauser <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: tklauser

doc/go1.16.html

@@ -865,9 +865,10 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
 <dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
   <dd>
     <p><!-- CL 248341, golang.org/issues/40281 -->
-      <code>StructTag</code> now allows multiple space-separated keys
-      in key:value pairs, as in <code>`json xml:"field1"`</code>
-      (equivalent to <code>`json:"field1" xml:"field1"`</code>).
+      <a href="/pkg/reflect/#StructTag"><code>StructTag</code></a>
+      now allows multiple space-separated keys in key:value pairs,
+      as in <code>`json xml:"field1"`</code> (equivalent to
+      <code>`json:"field1" xml:"field1"`</code>).
     </p>
   </dd>
 </dl><!-- reflect -->