Add C# code examples to the docs

Only existing GDScript code examples are converted and added to the
docs.
This is the first batch include classes beginning with A and B.

Included classes:
 * AcceptDialog
 * AESContext
 * Animation
 * AnimationNodeStateMachine
 * AnimationNodeStateMachinePlayback
 * AnimationNodeStateMachineTransition
 * Array
 * ArrayMesh
 * AStar
 * AStar2D
 * Bool
 * Button

doc/classes/AnimationNodeStateMachineTransition.xml

@@ -12,9 +12,14 @@
 	<members>
 		<member name="advance_condition" type="StringName" setter="set_advance_condition" getter="get_advance_condition" default="@&quot;&quot;">
 			Turn on auto advance when this condition is set. The provided name will become a boolean parameter on the [AnimationTree] that can be controlled from code (see [url=https://docs.godotengine.org/en/latest/tutorials/animation/animation_tree.html#controlling-from-code][/url]). For example, if [member AnimationTree.tree_root] is an [AnimationNodeStateMachine] and [member advance_condition] is set to [code]"idle"[/code]:
-			[codeblock]
-			$animation_tree["parameters/conditions/idle"] = is_on_floor and (linear_velocity.x == 0)
-			[/codeblock]
+			[codeblocks]
+			[gdscript]
+			$animation_tree.set("parameters/conditions/idle", is_on_floor and (linear_velocity.x == 0))
+			[/gdscript]
+			[csharp]
+			GetNode&lt;AnimationTree&gt;("animation_tree").Set("parameters/conditions/idle", IsOnFloor &amp;&amp; (LinearVelocity.x == 0));
+			[/csharp]
+			[/codeblocks]
 		</member>
 		<member name="auto_advance" type="bool" setter="set_auto_advance" getter="has_auto_advance" default="false">
 			Turn on the transition automatically when this state is reached. This works best with [constant SWITCH_MODE_AT_END].