Webhelp: html validation fixes

html validation fixes for easy search at http://inspirehep.net/help/easy-search

see

http://validator.w3.org/check?uri=http%3A%2F%2Finspirehep.net%2Fhelp%2Feasy-search&charset=%28detect+automatically%29&doctype=Inline&group=0&ss=1&outline=1