Edits to [[:Appendix:Lojban/denpa bu]]

I apologize for the undo; I wasn't aware of your motivations for rolling back to my previous edit. It looks like Lojban editors have moved on from the letteral macro I once observed them to use, and in fact most other letterals are now using, e.g., {{jbo-cmavo|selma'o=BY2}}. Appendix:Lojban/slaka bu needs some manner of update as well, given that it's using direct formatting rather than a macro for its headword line, and a number of the other letter names are not consistently formatted. Regardless, the entries are functional as they are.