update URL on the compare.html to OSM-FR server

[skorasaurus]

While preparing for the presentation (and making GIFs of comparisons between maps), I noticed the tile URL in compare.html was on your own server, fluv, the old home of the HDM tiles. ;)

Unimportant, but thought to push this because I was making this change anyways.

[yohanboniface]

Nice catch :)

But note that production URL is "{s}.tile.openstreetmap.fr", not "{s}.layers", which is QA server from OSM-fr ;)

[skorasaurus]

fixed. ;)

[yohanboniface]

Merged, thanks :)