updated Docs to include Extensions sub foldout and HandPhysicsService

Author: radicalad

Documentation/Extensions/ExtensionServices.md

@@ -3,7 +3,7 @@
 Extension services are components that extend the functionality of the Mixed Reality Toolkit. These services may be provided
 by the MRTK or by other parties.
 
-## Creating an extenison service
+## Creating an extension service
 
 The most efficient way to create an extension service is to use the [extension service creation wizard](../Tools/ExtensionServiceCreationWizard.md).
 To start the extension service creation wizard, select **Mixed Reality Toolkit > Utilities > Create Extension Service**.

Documentation/Extensions/HandPhysicsService/HandPhysicsServiceOverview.md

@@ -0,0 +1,29 @@
+# Hand Physics Extension Service
+The Hand Physics service enables rigid body collision events and interactions with articulated hands.
+
+## Enabling the extension
+To enable the extension, open your RegisteredServiceProvider profile. Click Register a new Service Provider to add a new configuration. In the Component Type field, select HandPhysicsService. In the Configuration Profile field, select the default hand physics profile included with the extension.
+
+## Profile Options
+### Hand Physics Layer
+Controls the layer the instantiated hand joints will go to.
+
+While the service defaults to the "default" layer (0), it is recommended to use a separate layer for Hand Physics objects. Otherwise there may be unwanted collisions and/or inaccurate raycasts.
+
+### Finger Tip Kinematic Body Prefab
+Controls which prefab is instantiated on fingertips. In order for the service to work as expected, the prefab requires:
+- A rigidbody component, with isKinematic enabled
+- A collider
+- `JointKinematicBody` component
+
+### Use Palm Kinematic Body
+Controls whether the service will attempt to instantiate a prefab on the palm joint.
+
+### Palm Kinematic Body Prefab
+When UsePalmKinematicBody is enabled, this is the prefab it will instantiate. Just like `FingerTipKinematicBodyPrefab`, this prefab requires:
+- A rigidbody component, with isKinematic enabled
+- A collider
+- `JointKinematicBody` component
+
+## How to use the service
+Once enabled, use any collider's `IsTrigger` property to receive collision events from all 10 digits (and palms if they're enabled).

Documentation/toc.yml

@@ -175,9 +175,13 @@
     - name: Runtime tools
       items:
       - name: Controller Mapping tool
-        href: Tools/ControllerMappingTool.md 
-  - name: Scene Transition Service
-    href: Extensions/SceneTransitionService/SceneTransitionServiceOverview.md
+        href: Tools/ControllerMappingTool.md
+  - name: Extensions
+    items:
+    - name: Scene Transition Service
+      href: Extensions/SceneTransitionService/SceneTransitionServiceOverview.md
+    - name: Hand Physics Service
+      href: Extensions/HandPhysicsService/HandPhysicsServiceOverview.md
 - name: Contributing
   items:
   - name: Contributing Overview