Create Documentation about exact Backup file format and content (including XML elements and attributes)

In order to asure our Backups are still valid in future version we need some kind of documentation.

It might be possible to generate the documentation from the Java Classes, similar to the SOAP/REST API.

It will be important to note in the documentation which attribute is available since what backup/openmeetings version.

However it needs also some general information about the layout of the ZIP file and where the other files like uploaded documents, recordings, profile images and recordings are stored in the ZIP.

The docs should also indicate how to correctly add new attributes and mark them with the @Version tag to make the Import/Export backwards compatible:
http://simple.sourceforge.net/download/stream/doc/tutorial/tutorial.php#version