It is really nice to have examples, but I was looking for was reference. I do understand that it covers some part of functionality, but is it all?
If you look at this example you will find that you can change:
o) public date,
o) powered by logo
o) include 3 types of generated content
o) change skins
o) and use expressions
Is this all?
I doubt it.
Starting from small things:
o) publishDate can have format cool, but what is the syntax? You do not need to describe it, reference is enough.
o) when I inherit something from something I can have menu. Nice. But the code I found has not only menu, but menu items too. They have references, how they are described?
o) how many levels can be in menu?
o) what items can be in menu?
o) what kind of files can be referenced?
o) which of them are interpreted by site and regenerated?
o) how files are referenced? I see that there are different files are used in other projects and they are referenced the same, but they are picked from different locations
o) where is the definition of the files that can be included
o) schema definition for site.xml would be nice. Documentation is much easier to read, but I can deal with it. Of course I still will have no idea what these items are used for, but at least I will know what can be included in site.xml and validate it.
I like maven and site plugin. I think it can be useful, but without the information I can do very little with it (change logo for empty document).