Documentation for Linux abounds but finding it is sometimes a little challenging. Sometimes you find it as a man page, sometimes as an infotex document, sometimes as a html document, and sometimes as a Gnome document. And that's just on your local system--searching the Internet for documentation is often very fruitful.
To read documentation see dhelp or browse
http://localhost/doc/HTML/index.html file://localhost/usr/share/doc/HTML/index.html