Improve and document PackedDataContainer

doc/classes/PackedDataContainerRef.xml

@@ -1,9 +1,31 @@
 <?xml version="1.0" encoding="UTF-8" ?>
 <class name="PackedDataContainerRef" inherits="RefCounted" version="4.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
 	<brief_description>
-		Reference-counted version of [PackedDataContainer].
+		Internal class used by [PackedDataContainer].
 	</brief_description>
 	<description>
+		When packing nested containers using [PackedDataContainer], they are recursively packed into [PackedDataContainerRef] (only applies to [Array] and [Dictionary]). Their data can be retrieved the same way as from [PackedDataContainer].
+		[codeblock]
+		var packed = PackedDataContainer.new()
+		packed.pack([1, 2, 3, ["abc", "def"], 4, 5, 6])
+
+		for element in packed:
+		    if element is PackedDataContainerRef:
+		        for subelement in element:
+		            print("::", subelement)
+		    else:
+		        print(element)
+
+		# Prints:
+		# 1
+		# 2
+		# 3
+		# ::abc
+		# ::def
+		# 4
+		# 5
+		# 6
+		[/codeblock]
 	</description>
 	<tutorials>
 	</tutorials>
@@ -11,6 +33,7 @@
 		<method name="size" qualifiers="const">
 			<return type="int" />
 			<description>
+				Returns the size of the packed container (see [method Array.size] and [method Dictionary.size]).
 			</description>
 		</method>
 	</methods>