[DOCS] get_indexed, tween

(cherry picked from commit a164d593c0)

doc/classes/Object.xml

@@ -184,6 +184,8 @@
 			<argument index="0" name="property" type="NodePath">
 			</argument>
 			<description>
+				Get indexed object property by String.
+				Property indices get accessed with colon seperation, for example: [code]position:x[/code]
 			</description>
 		</method>
 		<method name="get_instance_id" qualifiers="const">

doc/classes/Tween.xml

@@ -170,7 +170,7 @@
 			<argument index="7" name="delay" type="float" default="0">
 			</argument>
 			<description>
-				Animates [code]property[/code] of [code]object[/code] from [code]initial_val[/code] to [code]final_val[/code] for [code]duration[/code] seconds, [code]delay[/code] seconds later.
+				Animates [code]property[/code] of [code]object[/code] from [code]initial_val[/code] to [code]final_val[/code] for [code]duration[/code] seconds, [code]delay[/code] seconds later. Setting the initial value to [code]null[/code] uses the current value of the property.
                 Use [enum TransitionType] for [code]trans_type[/code] and [enum EaseType] for [code]ease_type[/code] parameters. These values control the timing and direction of the interpolation. See the class description for more information
 			</description>
 		</method>