Pushed some docstrings

[Robert Goldman]

I pushed documentation strings for some of the bundle operations.

Open for comments about their accuracy, helpfulness, etc.

At some point I would also like to reopen the issue of how to sync up
docstrings and manual.  The SBCL manual seems to have a solution to this
problem. I'd be willing to use something like Didier's decIt, too.  But
I need a solution that wouldn't destroy the existing manual.  Prefer
TeXinfo, also. No Markdown need apply! ;-)