Function reference needs to fit the rest of the site

The [function reference](http://chebfun.github.io/docs/) (an HTML version of all the help text) needs to be polished to fit the rest of the website. The text is not formatted as valid Markdown, so it will probably have to remain as a monospaced block, but that’s all right. It should include public methods of all Chebfun-related classes.
