Adds new file for panel plugin mixin

docs/extend/plugins.md

@@ -65,6 +65,7 @@ Supported mixin classes are:
 - [ScheduleMixin](./plugins/schedule.md)
 - [SettingsMixin](./plugins/settings.md)
 - [UrlsMixin](./plugins/urls.md)
+- [PanelMixin](./plugins/panel.md)
 
 ## Installing a Plugin
 

docs/extend/plugins/panel.md

@@ -0,0 +1,7 @@
+---
+title: Panel Mixin
+---
+
+## PanelMixin
+
+The `PanelMixin` enables plugins to render custom content to "panels" on individual pages in the web interface.

docs/releases/0.7.0.md

@@ -75,6 +75,10 @@ Multiple improvements have been made to the docker installation process, most no
 
 [#2770](https://github.com/inventree/InvenTree/pull/2770) implements a major overhaul of the "order parts" wizard, with the form now making use of the API rather than being rendered on the server.
 
+### Panel Plugins
+
+[#2937](https://github.com/inventree/InvenTree/pull/2937) adds a new type of plugin mixin, which allows rendering of custom "panels" on certain pages. This is a powerful new plugin feature which allows custom UI elements to be generated with ease. Read more about this new mixin [here](../extend/plugins/panel.md).
+
 ## Bug Fixes
 
 | Pull Request | Description |