Fix incorrect documentation

The doc module info was wrong.

Change-Id: I489aa9ec6d742a29a55f42c1ba3758b98c1eed36
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/37840
Reviewed-by: Keir Mierle <keir@google.com>
Commit-Queue: Keir Mierle <keir@google.com>
diff --git a/docs/module_structure.rst b/docs/module_structure.rst
index 49db88d..aa8cbb7 100644
--- a/docs/module_structure.rst
+++ b/docs/module_structure.rst
@@ -457,7 +457,7 @@
 
 10. Add the new module to docs module
 
-    - Add in ``docs/BUILD.gn`` to ``pw_doc_gen("docs")``
+    - Add in ``docs/BUILD.gn`` to ``group("module_docs")``
 
 11. Run :ref:`module-pw_module-module-check`