There doesn't seem to be any current documentation covering LTTng 2.0, but maybe that's because the project is in transition. The LTTng 2.0 website, however, is here: LTTng Project
You can access extensive help information on how to use the LTTng plug-in to search and analyze captured traces via the Eclipse help system:
Help | Help Contents | LTTng Plug-in User Guide