não consigo adicionar algumas tag do html5 no eclipse, está assim o meu xmlns
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:ui="http://xmlns.jcp.org/jsf/facelets" xmlns:f="http://xmlns.jcp.org/jsf/core" xmlns:h="http://xmlns.jcp.org/jsf/html" xmlns:p="http://primefaces.org/ui">