message: Add Sidre list format to sphinx documentation
diff: @@ -226,6 +226,55 @@ Move and Copy Views
  view data; i.e., it is shared by the original and the new view in the
  destination group.
  +----------------------------
  +List Format
  +----------------------------
  +
  +The list format is an alternate way for a group to hold its child groups and
  +view. In this format, any number of child group or view items can be created to
  +be held and accessed like a list, using iterators that iterate in the order
  +that they were added to the parent group. Child groups and views held in the
  +list format cannot be accessed by name.
  +
  +To create a group that uses the list format, the optional argument ``is_list``
  +must be set to ``true`` in the call to ``createGroup``.
  +
  + .. code-block:: C++
  +
  + // list_group will hold its child items in the list format.
  + Group* list_group = group->createGroup("my_list", true);
  +
  +It is recommended but not required that the items held in the list format
  +be created without names. String names may be assigned to these items,
  +but the names will not be useful for accessing them from their parent
  +group, and none of the methods that access child items by name or path will
  +return a valid pointer. The method ``createUnnamedGroup`` is available to
  +create an unnamed child group, while unnammed views can be created by passing
  +an empty string to any of the several ``createView`` methods in the ``Group``
  +class.
  +
  + .. code-block:: C++
  +
  + Group* g0 = list_group->createUnnamedGroup();
  + Group* g1 = list_group->createUnnamedGroup();
  + Group* g2 = list_group->createUnnamedGroup();
  + View* v0 = list_group->createView("");
  + View* v1 = list_group->createViewScalar("", 1.0);
  + View* v2 = list_group->createViewString("", "foo");
  + View* v3 = list_group->createViewg("", type, num_elems, buffer);
  +
  +While it is allowed to pass a non-empty string to be the name of a child
  +item held in the list format, a string with path syntax, (such as
  +``"foo/bar/baz"``) will be considered invalid, and the object creation methods
  +will return a null pointer if such a string is provided.
  +
  + .. code-block:: C++
  +
  + // This is valid, but the string name will not be useful for future access.
  + View* foo = list_group->createView("foo");
  + // This is invalid due to the path syntax, a nullptr will be returned.
  + View* baz = list_group->createView("bar/baz");
  +
  ----------------------------
  Group I/O Operations
  ----------------------------
  