Update index.html

Corrected listing for Windows by adding missing fonts from http://msdn.microsoft.com/en-us/library/windowsphone/develop/cc189010%28v=vs.105%29.aspx#silverlight_fonts

Added in a few missing iOS fonts too, based on the "Typefaces" app which shows the actual installed fonts.
Merge pull request #2 from clagnut/patch-1

Update index.html