Handling of empty classes (no attributes) in auto-generated markdown documentation

[el-wiss]

On rare occasions, models can contain classes with no attributes (such as SIA405 Base) with its BaseClass.
The table with its headers is still created, but remains empty, which is suboptimal when viewing the documentation.

It is clearly an edge case and technically not a bug, but maybe the behaviour could be enhanced by introducing a simple check for attributes, and if the number is zero, the insertion of a placeholder such as "keine Attribute in dieser Klasse"?