Add VRChat and GitHub packages to Unity project

Assets/Udon/ReferenceDocs/_sources/nodes/System/index.rst.txt

@@ -0,0 +1,28 @@
+====================================================================================================================================================
+System
+====================================================================================================================================================
+
+The System module.
+
+.. toctree::
+   :maxdepth: 1
+   :caption: Nodes:
+
+   Boolean/index
+   Byte/index
+   Char/index
+   Convert/index
+   DateTime/index
+   Double/index
+   Int16/index
+   Int/index
+   Int64/index
+   Object/index
+   SByte/index
+   Float/index
+   String/index
+   TimeZoneInfo/index
+   Type/index
+   UInt16/index
+   Uint/index
+   UInt64/index