Added minimal plugin docs

Author: jath03

docs/index.rst

@@ -13,6 +13,7 @@ Welcome to OpenRGB-Python's documentation!
    pages/intro
    pages/usage
    pages/effects
+   pages/plugins
    pages/advanced
    pages/faq
    pages/api

docs/pages/plugins.rst

@@ -0,0 +1,14 @@
+Plugins
+=======
+
+OpenRGB recently (0.81) added support for SDK clients to interact with plugins.  This
+means that you can control plugins from the SDK.  I wrote a basic integration with
+the effects plugin as a proof of concept, but it is very flexible and can support more
+advanced use cases if someone writes the code.  Any plugins that support SDK
+interactions will be listed under the :any:`plugins<OpenRGBClient.plugins>`
+
+
+`OpenRGBEffectsPlugin<https://gitlab.com/OpenRGBDevelopers/OpenRGBEffectsPlugin>`_
+-----------------------------------------------------------------------------------
+
+