Documentation should not be handled differently than source code.
It is typically managed as elements and thus an issue of
Version control (although there could
be derived objects as well, resulting of some processing).
The dependencies are however typically not generated during the
build, and should therefore be maintained in some specific way.
The problem of relevance: documentation is needed, but where, when and for whom? Different pieces of information are needed in different contexts, even to document the same thing! Documentation may be a burden.
It is possible to use ClearCase hyperlinks to support the relationship between a source file and its documentation.