+ open-iconic/update.json, needs opinion

So seems the [WebP](https://github.com/jsdelivr/jsdelivr/tree/master/files/open-iconic/1.1.0/webp) images were uploaded, but not the far more browser-supported [PNG](https://github.com/iconic/open-iconic/tree/master/png)s.  1300 images is alot but 1300*2*new version every 3-4 months is alot.

Maybe drop both until people ask for them?  Really the thrust of Iconic is individual SVG images.  The fonts & raster images are provided as a backup.  No one complained that the PNGs were missing, even though they're required by IE8.  (& IMHO SVG should be THE format for icons).

@somerandomdude this file is for automated uploads to the CDN.