Update scene_composer.adoc

Corrected mouse click documentation.
Added hotkeys for manipulating objects.

docs/modules/sdk/pages/scene_composer.adoc

@@ -14,11 +14,20 @@ Most buttons in the SceneComposer have tooltips that appear when you hover the m
 *  Left-click and drag to rotate the camera around the cam center
 *  Right-click and drag to move the cam center
 *  Scroll the mouse wheel to zoom in/out the cam center
-*  Left-click a geometry to select it
-*  Right-click a geometry to place the cursor
+*  Right-click a geometry to select it
+*  Left-click a geometry to place the cursor
 
 In the SceneComposer toolbar are buttons to snap the camera to the cursor, snap the cursor to the selection and etc.
 
+Hot keys for manipulating objects:
+
+G - Move
+R - Rotate
+S - Scale
+
+In addition, you can limit the manipulation to a certain axis by pressing X, Y, or Z.
+By default the object's local reference will be used. Global or Camera reference can be selected in the SceneComposer window.
+
 
 == Creating a scene file