Drop future syntax for variable font hints

[danburzo]

Thank you for the excellent resource!

The current css-fonts-4 spec has an updated syntax for variable font hints: format(woff2) tech(variations). Neither this syntax (which, due to CSS parsing rules needs to be added as a second src declaration), nor previous incarnations (such as the one presented on the website) has any browser support. On the flipside, format('woff2-variations') is supported now and hopefully forever.

I believe it would be better to drop the new syntax altogether.