assembly info proposal

--------------------------------------------------------------
Some wanted to use info for metadata about the assembly
elements themselves, following the pattern of other docbook
elements where an info element documents its parent.

Bob mentioned that using info in module where content is
being specified was confusing, since that location
implies using info as an override.

Larry pointed out that the element name
"override" in module was not always appropriate.
In the case of a module that specifies renderas="chapter"
and has no resourceref attribute, then a title specified in
that module would not be overriding anything.
Perhaps "contentinfo" would be more general.
---------------------------------------------------------------