Added a section regarding --plugin

Author: Torxed

docs/archinstall/plugins.rst

@@ -0,0 +1,48 @@
+.. _archinstall.Plugins:
+
+Python Plugins
+==============
+
+``archinstall`` supports plugins via two methods.
+
+First method is directly via the ``--plugin`` parameter when running as a CLI tool. This will load a specific plugin locally or remotely via a path.
+
+The second method is via Python's built in `plugin discovery`_ using `entry points`_ categorized as ``archinstall.plugin``.
+
+``--plugin`` parameter
+----------------------
+
+The parameter has the benefit of being stored in the ``--conf`` state, meaning when re-running an installation — the plugin will automatically be loaded.
+It's limitation is that it requires an initial path to be known and written and be cumbersome.
+
+Plugin Discovery
+----------------
+
+This method allows for multiple plugins to be loaded with the drawback that they have to be installed beforehand on the system running ``archinstall``.
+This mainly targets those who build their own ISO's and package specific setups for their needs.
+
+
+What's supported?
+-----------------
+
+Currently the documentation for this is scarse. Until that is resolved, the best way to find supported features is to search the source code for `plugin.on_ <https://github.com/search?q=repo%3Aarchlinux%2Farchinstall+%22plugin.on_%22&type=code>`_ as this will give a clear indication of which calls are made to plugins.
+
+How does it work?
+-----------------
+
+``archinstall`` plugins use a discovery-driven approach where plugins are queried for certain functions.
+As an example, if a plugin has the following function:
+
+.. code-block:: python
+
+   def on_pacstrap(*packages):
+       ...
+
+The function :code:`archinstall.Pacman().strap(["some packages"])` is hardcoded to iterate plugins and look for :code:`on_pacstrap` in the plugin.
+If the function exists, :code:`.strap()` will call the plugin's function and replace the initial package list with the result from the plugin.
+
+The best way to document these calls is currently undecided, as it's hard to document this behavior dynamically.
+
+
+.. _plugin discovery: https://packaging.python.org/en/latest/specifications/entry-points/
+.. _entry points: https://docs.python.org/3/library/importlib.metadata.html#entry-points

docs/index.rst

@@ -34,6 +34,7 @@ Some of the features of Archinstall are:
 
    installing/python
    examples/python
+   archinstall/plugins
 
 .. toctree::
    :maxdepth: 3