Pushed some docstrings

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! ;-)