doc/site/build-ref.html: fix export error

Fixes #9124

PiperOrigin-RevId: 262356093

site/docs/build-ref.html

diff --git a/site/docs/build-ref.html b/site/docs/build-ref.html
index 0f29c4f..52f9c15 100644
--- a/site/docs/build-ref.html
+++ b/site/docs/build-ref.html
@@ -201,6 +201,12 @@
   this label is usually written as
 </p>
 
+<pre>
+//my/app/main:app_binary
+</pre>
+
+<p>
+
   Each label has two parts, a package name (<code>my/app/main</code>)
   and a target name (<code>app_binary</code>).  Every label uniquely
   identifies a target.  Labels sometimes appear in other forms; when