mod support design wip

assets/modules/modules_doc.md

@@ -0,0 +1,14 @@
+Modules may have following subdirectories:
+
+- creatures
+- factions
+- items
+- tiles
+- weathers
+
+
+Modules must be packed with Terrarum Virtual Disk format. The packer is located in
+
+    lib/TerranVirtualDisk.jar
+
+For more information, please refer to [this link](https://github.com/minjaesong/TerranVirtualDisk)