[html5] HTML5 validation should use MathML 3.0 not MathML 2.0

[Joe Java]

Hello

  HTML5 documents that use MathML are validated at:

http://validator.nu/

as:

HTML5+ARIA, SVG 1.1 plus MathML 2.0 

but should be validated on MathML 3.0 not MathML 2.0

(MathML 3.0 was approved October 21, 2010)

   Joe