Fixes `parser.clean()` reported in issue #16820.
diff --git a/Doc/library/configparser.rst b/Doc/library/configparser.rst
index 958375b..0b8212c 100644
--- a/Doc/library/configparser.rst
+++ b/Doc/library/configparser.rst
@@ -389,7 +389,13 @@
the default value to be visible again. Trying to delete a default value
causes a ``KeyError``.
-* Trying to delete the ``DEFAULTSECT`` raises ``ValueError``.
+* ``DEFAULTSECT`` cannot be removed from the parser:
+
+ * trying to delete it raises ``ValueError``,
+
+ * ``parser.clear()`` leaves it intact,
+
+ * ``parser.popitem()`` never returns it.
* ``parser.get(section, option, **kwargs)`` - the second argument is **not**
a fallback value. Note however that the section-level ``get()`` methods are