Update text about restricted HTML5 support in browsers in JSP vs Thymeleaf documentation

[alanoe]

In section 5 (Got HTML5?) of https://www.thymeleaf.org/doc/articles/thvsjsp.html , it is said "Unfortunately not all browsers support this yet (as of 2011, Opera 11 and Firefox 4 do)". This commend is outdated, as all popular browsers support HTML5 nowadays.