Add uuid to sidebar, update relevant files

Author: CrashTestJava

api/layer.md

@@ -84,7 +84,7 @@ parent.
 local uuid = layer.uuid
 ```
 
-Returns the uuid of the layer.
+Returns the [uuid](uuid.md#uuid) of the layer.
 
 ## Layer.isImage
 

sidebar.md

@@ -64,5 +64,6 @@ Classes/objects
   * [Tool](api/tool.md#tool)
   * [TouchEvent](api/touchevent.md#touchevent)
   * [Version](api/version.md#version)
+  * [Uuid](api/uuid.md#uuid)
   * [WebSocket](api/websocket.md#websocket)
   * [Window](api/window.md#window)