Document the --experimental_extra_action_top_level_only command line option.
RELNOTES: None.
@@ -1075,6 +1075,16 @@ $ bazel fetch //...
><code>extra_actions</code></a> into the build graph.
</p>
+<h4 id='flag--experimental_extra_action_top_level_only'>
+ <code class='flag'>--[no]experimental_extra_action_top_level_only</code>
+</h4>
+<p>
+ If this option is set to true, extra actions specified by the
+ <a href='#flag--experimental_action_listener'> <code>
+ --experimental_action_listener</code></a> command line option will only be
+ scheduled for top level targets.
+</p>
+
<h4 id='flag--experimental_extra_action_filter'>
<code class='flag'>--experimental_extra_action_filter=<var>regex</var></code>
</h4>
