Backfill CHANGELOG.md for 4.0.4 -> 4.1.7
Backfill CHANGELOG.md for 4.0.4 -> 4.1.7

Thanks for all the work @aFarkas I did my best to backfill the Changelog and hope I did not miss anything vital. Hope you can make use of it.
aFarkas/lazysizes,aFarkas/lazysizes