I have stopped using confluence wiki for design notes because well, it converts everything into wiki pages that aren't particularly maintainable.
I am trying asciidoc. The attached file is an asciidoc design note with diagrams that are automatically rendered. Get the asciidoc plugin for chrome (Note: the firefox version of this plugin is not working currently) In the preferences/settings for the plugin, enable the diagrams feature. You can then look at the file and see the UML diagrams which are created from text descriptions in the document.
