Docstring processors are thirteen to a dozen, and those derived from SBCL's docstrings.lisp are a legion of their own.
I've been guilty of copying SBCL's docstrings.lisp to various projects myself, hand tweaking it to suit their needs... till finally I found myself with a half a dozen divergent copies. Eugh.
So, SB-TEXINFO was born: it should contain tweaks from all my copies, merged back on top of SBCL's upstream copy.
I plan to merge it back to SBCL as a contrib once I'm happy with it, but the schedule is still open on that.