warp: add example of normal exception handling to Warp.hs haddocks
warp: add example of normal exception handling to Warp.hs haddocks

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