Adds docs for locate mixin class

docs/extend/plugins.md

@@ -61,6 +61,7 @@ Supported mixin classes are:
 - [BarcodeMixin](./plugins/barcode.md)
 - [EventMixin](./plugins/event.md)
 - [LabelPrintingMixin](./plugins/label.md)
+- [LocateMixin](./plugins/locate.md)
 - [NavigationMixin](./plugins/navigation.md)
 - [PanelMixin](./plugins/panel.md)
 - [ScheduleMixin](./plugins/schedule.md)

docs/extend/plugins/locate.md

@@ -0,0 +1,31 @@
+---
+title: Locate Mixin
+---
+
+## LocateMixin
+
+The `LocateMixin` class enables plugins to "locate" stock items (or stock locations) via an entirely custom method.
+
+For example, a warehouse could be arranged with each individual 'parts bin' having an audio-visual indicator (e.g. RGB LED and buzzer). "Locating" a particular stock item causes the LED to flash and the buzzer to sound.
+
+Another example might be a parts retrieval system, where "locating" a stock item causes the stock item to be "delivered" to the user via a conveyor.
+
+The possibilities are endless!
+
+### Web Integration
+
+{% with id="web_locate", url="plugin/web_locate.png", description="Locate stock item from web interface", maxheight="400px" %}
+{% include 'img.html' %}
+{% endwith %}
+
+### App Integration
+
+If a locate plugin is installed and activated, the [InvenTree mobile app](../../app/app.md) displays a button for locating a StockItem or StockLocation (see below):
+
+{% with id="app_locate", url="plugin/app_locate.png", description="Locate stock item from app", maxheight="400px" %}
+{% include 'img.html' %}
+{% endwith %}
+
+### Implementation
+
+Refer to the [InvenTree source code](https://github.com/inventree/InvenTree/blob/master/InvenTree/plugin/samples/locate/locate_sample.py) for a simple implementation example.