I don't have a strict policy myself. Since POD is basically a free-form text language I just do whatever reads best in context. As well as what you outlined some other structures I use are:

• List the exceptions thrown by themodule in a separate "Exceptions" section - useful if their are common exceptions thrown by many methods.
• Use a list rather than a preformatted text section - useful if your exception descriptions are complex.
• Use a separate document. I often have a single module that defines all the exceptions I use in my application (I like Exception::Class). I document all exceptions here and reference from the other modules. Gives you the advantage of having a single reference point.