inventory plugin order: update doc

add doc for #44428:
- add changelog fragment
- update porting guide
also:
- update auto inventory plugin doc
- mention toml plugin in examples

docs/docsite/rst/plugins/inventory.rst

@@ -22,7 +22,7 @@ config file that ships with Ansible:
 .. code-block:: ini
 
    [inventory]
-   enable_plugins = host_list, script, auto, yaml, ini
+   enable_plugins = host_list, script, auto, yaml, ini, toml
 
 This list also establishes the order in which each plugin tries to parse an inventory source. Any plugins left out of the list will not be considered, so you can 'optimize' your inventory loading by minimizing it to what you actually use. For example:
 

docs/docsite/rst/porting_guides/porting_guide_2.8.rst

@@ -139,6 +139,8 @@ Plugins
   has changed to ``%USERPROFILE%\.ansible_async``. To control this path now, either set the ``ansible_async_dir``
   variable or the ``async_dir`` value in the ``powershell`` section of the config ini.
 
+* Order of enabled inventory plugins (:ref:`INVENTORY_ENABLED`) has been updated, :ref:`auto <auto_inventory>` is now before :ref:`yaml <yaml_inventory>` and :ref:`ini <ini_inventory>`.
+
 Porting custom scripts
 ======================