In the project
We use a single wiki for all developer documentation. It is this one from the http://argouml.tigris.org project.
Each tigris project has a wiki provided and the ArgoUML project is spread over many many tigris projects.
We also have a separate users' wiki, at http://www.argouml-users.net for discussions on how to use ArgoUML.
Details
For code snippets, class, and method names, we use the code markup ( { { { and } } } without the spaces), like this: Model.getFacade().
For filename references we use bold like this: Model.java.
When mentioning a replacable part we use italics. For filenames that will be both bold and italics like this TypeFactory.java.
For commands issued in the shell or command window we use the code markup since this is a special case of code, like this: ./build.sh tests.