[tex-live] Mention new microtype in TL13 news

[Uwe Siart]

As far as I understand the new version of microtype that comes with TL13
now enables microtype features for the xetex and luatex engines. To my
thinking this is a rather large milestone in TL13 over TL12 (even though
not directly related to TL development). So if you think that it is
worth mentioning this in the TL13 news section I suggest to add it
there.

-- 
Uwe