Add entity query changelog entry (#593)

* add changelog

* wrong name

* more sami feedback

Author: jamiebrynes7

CHANGELOG.md

@@ -10,6 +10,9 @@
 - Added support for local mobile development.
 - Added a changelog.
 - Added field level dirty markers in components. This allows for partial automatic component updates to be sent.
+- Added full support for `EntityQuery` world commands.
+    - Added `Improbable.Gdk.Core.EntityQuerySnapshot` to hold the result of a single entity from a snapshot query.
+    - Added `Improbable.Gdk.Core.ISpatialComponentSnapshot` to differentiate between a snapshot of component state and component data.
 
 ### Changed
 
@@ -43,4 +46,4 @@
 
 ## `0.1.0` - 2018-10-10
 
-The initial alpha release of the SpatialOS GDK for Unity.
+The initial alpha release of the SpatialOS GDK for Unity.