Documentation Improvements (#4894)

* Improvements for version banner

- Display at the bottom of the page
- Simplify text

* Use mkdocs version provider

* use 'navigation.instant'

* Support modern mkdocs features

- Much better navigation and improved features

* Content changes

* Add code to find previous versions

* Remove modern python syntax

* display output codes

* Hide version banner

* Extra debug message

* update terminology.md

docs/docs/extend/how_to_plugin.md

@@ -1,8 +1,9 @@
 ---
-title: How to plugin
+title: Developing Plugins
 ---
 
-## How to write a plugin
+## How to Develop a Plugin
+
 A short introductory guide for plugin beginners.
 
 ### Should it be a plugin?

docs/docs/extend/plugins.md

@@ -89,17 +89,19 @@ Common use cases are covered by pre-supplied modules in the form of *mixins* (si
 
 Supported mixin classes are:
 
-- [ActionMixin](./plugins/action.md)
-- [APICallMixin](./plugins/api.md)
-- [AppMixin](./plugins/app.md)
-- [BarcodeMixin](./plugins/barcode.md)
-- [EventMixin](./plugins/event.md)
-- [LabelPrintingMixin](./plugins/label.md)
-- [LocateMixin](./plugins/locate.md)
-- [NavigationMixin](./plugins/navigation.md)
-- [PanelMixin](./plugins/panel.md)
-- [ReportMixin](./plugins/report.md)
-- [ScheduleMixin](./plugins/schedule.md)
-- [SettingsMixin](./plugins/settings.md)
-- [UrlsMixin](./plugins/urls.md)
-- [ValidationMixin](./plugins/validation.md)
+| Mixin | Description |
+| --- | --- |
+| [ActionMixin](./plugins/action.md) | Run custom actions |
+| [APICallMixin](./plugins/api.md) | Perform calls to external APIs |
+| [AppMixin](./plugins/app.md) | Integrate additional database tables |
+| [BarcodeMixin](./plugins/barcode.md) | Support custom barcode actions |
+| [EventMixin](./plugins/event.md) | Respond to events |
+| [LabelPrintingMixin](./plugins/label.md) | Custom label printing support |
+| [LocateMixin](./plugins/locate.md) | Locate and identify stock items |
+| [NavigationMixin](./plugins/navigation.md) | Add custom pages to the web interface |
+| [PanelMixin](./plugins/panel.md) | Add custom panels to web views |
+| [ReportMixin](./plugins/report.md) | Add custom context data to reports |
+| [ScheduleMixin](./plugins/schedule.md) | Schedule periodic tasks |
+| [SettingsMixin](./plugins/settings.md) | Integrate user configurable settings |
+| [UrlsMixin](./plugins/urls.md) | Respond to custom URL endpoints |
+| [ValidationMixin](./plugins/validation.md) | Provide custom validation of database models |