I am not one of the book/site's authors, but one of the Kepler commiters :-), but this is what they say at the site's about page:
"This website is powered entirely by Lua, using Sputnik, an extensible wiki package. When the authors and contributers were compiling the electronic API reference, Lua tables were chosen as the data file format, due to it's extreme flexibility and readability. When the time came to produce the online version of the reference, a Lua-based solution was obviously attractive."
As for the wiki's author, he was studying software projects based on Brazil as part of his PhD at UC Berkeley School of Information and decided to stick around and participate.
"This website is powered entirely by Lua, using Sputnik, an extensible wiki package. When the authors and contributers were compiling the electronic API reference, Lua tables were chosen as the data file format, due to it's extreme flexibility and readability. When the time came to produce the online version of the reference, a Lua-based solution was obviously attractive."
As for the wiki's author, he was studying software projects based on Brazil as part of his PhD at UC Berkeley School of Information and decided to stick around and participate.