Lambda and Function docstrings render better.

docs/docs/parser.rst

@@ -22,7 +22,7 @@ All nodes and leaves have these methods/properties:
 
 
 Python Parser Tree
------------------
+------------------
 
 .. automodule:: jedi.parser.python.tree
     :members:

jedi/parser/python/tree.py

@@ -450,7 +450,8 @@ class Function(ClassOrFunc):
     """
     Used to store the parsed contents of a python function.
 
-    Children:
+    Children::
+
         0. <Keyword: def>
         1. <Name>
         2. parameter list (including open-paren and close-paren <Operator>s)
@@ -520,7 +521,7 @@ class Lambda(Function):
     """
     Lambdas are basically trimmed functions, so give it the same interface.
 
-    Children:
+    Children::
 
          0. <Keyword: lambda>
          *. <Param x> for each argument x