Expand docstrings of new nodes' classes

Author: TLouf

sphinx/addnodes.py

@@ -242,14 +242,26 @@ def astext(self) -> str:
 
 
 class desc_parameterlist(nodes.Part, nodes.Inline, nodes.FixedTextElement):
-    """Node for a general parameter list."""
+    """Node for a general parameter list.
+
+    As default the parameter list is written in line with the rest of the signature.
+    Set ``is_multi_line = True`` to describe a multi-line parameter list. In that case
+    all child nodes must be :py:class:`desc_parameter_line` nodes, and each parameter
+    will then be written on its own, indented line.
+    """
     child_text_separator = ', '
 
     def astext(self):
         return f'({super().astext()})'
 
 
 class desc_parameter_line(nodes.General, nodes.Element):
+    """Node for a single, indented parameter line.
+
+    It should only be used as a child of a :py:class:`desc_parameterlist` with
+    ``is_multi_line`` set to ``True``, and have a single :py:class:`desc_parameter`
+    child.
+    """
 
 
 class desc_parameter(nodes.Part, nodes.Inline, nodes.FixedTextElement):