The hyperspec is copyrighted and licensed in a way where we can't change it at all. It's like the primary source to learn so impossible for anyone knowledgeable to clean-room reverse engineer a new one.
At least in my country you'd be perfectly within your rights to distribute a program that would modify it automatically for every reader who'd want to read a modified version, since as per our copyright act, you're entitled to do pretty much any modifications to the copyrighted works that you possess, as long as you don't redistribute them.
http://clhs.lisp.se/Front/Help.htm#Legal
>Permission to copy, distribute, display, and transmit the Common Lisp HyperSpec is granted provided that copies are not made or distributed or displayed or transmitted for direct commercial advantage, that notice is given that copying, distribution, display, and/or transmission is by permission of LispWorks Ltd., and that any copy made is COMPLETE and UNMODIFIED. IN PARTICULAR, the material that MUST appear in the copy includes:
>...
>Permissions related to performance and to creation of derivative works are expressly NOT granted.
>Permission to make modified copies is expressly NOT granted.
>Permission to add or replace any links or any graphical images to any of these pages is expressly NOT granted.