docs/features: remove a few redundant zink mentions
GL 4.1 and 4.2 is listed as done for Zink anyway, so we don't need to single out these features as supported any longer. Reviewed-by:Hoe Hao Cheng <haochengho12907@gmail.com> Part-of: <!8639>
GL 4.1 and 4.2 is listed as done for Zink anyway, so we don't need to single out these features as supported any longer. Reviewed-by: