Update emmet/snippets.json

changed snippets for html:4t, html:4s, html:xt, html:xs, html:xxs, html:5.

Detail: changed all
    <body>\n\t${child}${2}\n</body>
to
    <body>\n\t${child}$0\n</body>

Why:
I see no point that every time people start a new html, having to tab to be end then go back to the body. Or pressing <ESC> when inside the body tag.