An Opening Page for Variants

[CormacOBear]

Some members of the content team have expressed interest in collecting known Variant Openings and uploading them to a library similar to https://lichess.org/opening. Possibly starting with 3check though there seem to be more opening materials for antichess and atomic.

The ongoing discussions are on the content discord: https://discord.com/channels/1094189632691904573/1293611668735266846