docs: show __init__ docstrings (#504)

http://www.sphinx-doc.org/en/stable/ext/autodoc.html#confval-autoclass_content

docs/conf.py

@@ -100,6 +100,8 @@ pygments_style = 'sphinx'
 # If true, `todo` and `todoList` produce output, else they produce nothing.
 todo_include_todos = False
 
+# Both the class' and the __init__ method's docstring are concatenated and inserted.
+autoclass_content = 'both'
 
 # -- Options for HTML output ----------------------------------------------