doc update.
doc update.

sordina/wai,tolysz/wai,creichert/wai,yesodweb/wai,tolysz/wai,sordina/wai,sordina/wai,sordina/wai,tolysz/wai,kazu-yamamoto/wai,tolysz/wai,kazu-yamamoto/wai,creichert/wai,yesodweb/wai