docs: autosectionlabel_maxdepth

doc/usage/extensions/autosectionlabel.rst

@@ -38,3 +38,10 @@ Configuration
    called ``Introduction`` that appears in document ``index.rst``.  Useful for
    avoiding ambiguity when the same section heading appears in different
    documents.
+
+.. confval:: autosectionlabel_maxdepth
+
+   If set, autosectionlabel chooses the sections for labeling by its depth. For
+   example, when set 1 to ``autosectionlabel_maxdepth``, labels are generated
+   only for top level sections, and deeper sections are not labeled.  It
+   defaults to ``None`` (disabled).